yes it's a dead horse, lets keep on beating the crap out of it ;-)
here's an idea...
http://www.vulcanforums.com/forums/showthread.php?t=24679
this person states the reason for stator failures is vibration, not load, not heat, perhaps
this is the real reason after all. the vision vibrates, live with it...
comments ?
if that be true, how many think moving the regulator to a different spot has or will increase stator life ?
I think it's heat mostly. Most of the dead stators I've pulled we're crispy at the top. I think they see less cooling oil there. I installed an oil cooler 8 years ago & the the Yamaha replacement stator is still going strong (knock wood)
I think moving the R/R TO COOLER AIR ALSO HELPED AS DID A SEMI SYNTHetic oil and eliminating the R/R connectors. (oops. Sorry)
Tourer generally runs just past center on the temp gauge & the fan only ever comes on after the bike is off on a hot day. I made sure to flush the cooling system and burp it well. I also tend to set my carbs slightly rich. That might contribute to it running cooler. It recently got an Agm battery and I'm hoping to put a MOSFET R/R in someday...
Sent from my iPhone using Tapatalk
Well, the Vision has a counter balance shaft and is very smooth and nearly vibration free. My VX has either a staggered crank pin or nothing at all. It generates quite a bit of vibration above 7000 rpm and at 8500 red line is actually a bit uncomfortable. Both use the G7 stator.
My VX had a factory stator which failed after 21 years of use, It had 3 coils which were brown , none were cindered. I installed a used stator from a 750 Virago. The RR is stock, but is moved to a location in front of the left rear shock , for better access and air flow . ( stock location is down by the swing arm in front of the rear tyre.)
The VX forum reports a very occasional failure , Not a chronic problem .
I installed a KZ900 RR, on the Vision, in 2003, It has a larger heat sink and is supposed to be better quality. I moved it out in the air stream , on the left foot peg /muffler mount. Both RR are hard wired in, as are the stators.
As I said many years ago on this forum , the Vision 's oil runs fairly hot. The oil is not present in much of a quantity to carry heat away from the stator ( the VX has much more oil in the stator case) I believe that the heat build up in the case results in premature stator failure. The oil needs to be cooler that the stator to carry the heat away. Either there is not enough oil to do this OR the oil is too hot and is actually adding heat to the stator. The G7 stator used in the Vision , is used in lots of other bike's, 4's, twins and singles. Most have a low incidence of failure.
I don't believe vibration has anything to do with it.
I think Rick is correct that vibration is not the cause. It COULD be if the stator windings were loose and flopping around but that is not the case. Most failed stators are quite dark in color, crispy and blistered even. I think heat is the usual cause for failure, though there can be other reasons.
Here is a good application of the much heralded MOSFET RR unit. Since the MOSFET units run cooler than the original RR units that shows me they are dissipating less heat, which leads me to believe they cause less stress on the stator. All the components in the charging system form a "chain", and by strengthening the weakest link the whole becomes stronger. That's my conjecture and I'm sticking to it.
This may seem like a somewhat radical idea, but what about having a machine shop drill a small hole diagonally through the flywheel, and into the center of the crank. This way the stator would be continuously sprayed with oil, all the way around the innermost side of the stator. Would that cause any problems to the rest of the oil system?
As already mentioned, the stators are usually burnt out at the top where little oil reaches it, causing me to believe that the main problem is that oil is not reaching the stator. Adding a mosfet r/r help keep the stator itself running cooler, and adding an oil cooler helps cool what ever oil reaches, but if the top half of the stator is receiving little oil it is still likely to burn out. If a lot of people think this is worth trying I might give it a shot, especially if I'm already having my crank ground down.
not radical at all, in fact a version has been done on the Venture.
a couple of the guys here have tried it but I don't recall if they ever posted a long term result.
personally I think it's inconclusive and I wouldn't want to risk modifying the oiling system
on the vision only to have a crank failure...
I agree that vibration isn't the real culprit, of course it is heat.
the difference is that we have some great minds around here and some excellent ideas
I really just wanted to stir up some further discussion on the topic
Rick, I understand what you are saying but is the suzuki stator completely immersed in oil ?
if the oil level was that high in the crankcase wouldn't that be a big power loss for that engine ?
does suzuki spray the stator in that motor ?
RM, Id tend to doubt that the oil is necessarily any hotter in a vision than any other bike, especially an air cooled one.
cooling oil that never reaches the stator would also seem a time waster. perhaps there is a way to funnel returning oil down over the stator on its way back to the crankcase... thoughts ?
-Ron
So, I am probably going to wake up some nasty, hungry gremlins by saying this..... It'd be interesting to compare a Vision that has not burnt a stator to one that has burnt several. So, given that YJ is still on the original stator, anyone close to TN that burns a lot of stators is welcome to have a seat on YJ and see if there is a difference between the two in vibration.
IMHO, YJ does not vibrate a lot so its a viable theory.
David
Any way to get the stator to run cooler should improve stator life. An oil cooler should reduce crankcase and stator temperature, even if not much oil actually gets to the stator. The type of regulator in use could have an effect also. Most regulators are of the shunt type. Unneeded phase current is shorted to ground. With a series regulator unneeded phase current is switched off. The lower average current flowing in a series regulated stator should lead to lower stator temperature. The Compufire 55402 appears to be a good Vision series regulator candidate. Assuming the MOSFET regulator discussed previously is of shunt design it won't directly improve stator life. However, it should be more reliable than a before MOSFET design.
Quote from: admin on September 30, 2012, 02:48:03 PMperhaps there is a way to funnel returning oil down over the stator on its way back to the crankcase... thoughts ?
If you wanted to try this I think your best bet would be to catch oil coming down through the rear cylinder cam chain chamber. The biggest problem would be making something that can catch most of the oil, and still allow clearance for the cam chain. Once you did that you would have to get the oil,between the flywheel and the stator cover which are very close together, and then around to the inside of the flywheel. The other option would be to try and take oil from the starter clutch bearing, which currently splashes oil back to the sump. If you could get this to work it might be a very good option, but I think getting it to work would be complicated.
I still think that adding a small hole as I mentioned would be a better/simpler option. Would it really be that much of an extra load on the system? The particular oil gallery it would be taking oil from is currently only supporting the starter clutch bearing, and is fed by the left side main bearing (which also feeds the front cylinder head through a small oil jet). Right now the starter clutch runs on a bushing with grooves in it, these grooves hold oil and allow oil an easy path back to the sump. Maybe using a bushing without grooves here could make up for a pressure loss caused by adding the extra hole in the flywheel?
I think it's good to beat a dead horse ;D There are always new members with fresh perspectives to add their 2 cents.
darkvision added heat sinks to the alternator cover and seemed to get measurable temp differences with them. Here's a pic in this thread:
http://ridersofvision.net/rovforum/index.php?topic=13269.msg120545#msg120545 (http://ridersofvision.net/rovforum/index.php?topic=13269.msg120545#msg120545)
He first mentioned it way back in '08 http://ridersofvision.net/rovforum/index.php?topic=9564.0 (http://ridersofvision.net/rovforum/index.php?topic=9564.0)and quite a lengthy discussion ensued that ran the gamut of theories. Page 2 has a pic from George Young showing where he drilled his flywheel bolt to spray oil on the stator. A subsequent stator failure had him comment the results were inconclusive. Page 3 has a reply from motoracer with oil temps he measured that suggest an oil cooler is superfluous.
Lots of interesting reading on the subject.
Did George do any other modifications besides drilling a hole in the end of the bolt. If not I do not think his modification would have had any chance oil getting extra oil to the top half of the stator. When the engine is assembled that bolt is enclosed in a little circular area, making it impossible for the oil spray to hit the stator directly. That said I didn't see anything about indications of low oil pressure, so that could provide me with some reassurance to try my idea.
I really like the heat sinks! Something like that could work very well for me, although I'm not sure I would have the room/airflow for it to work well. I wonder if I could pipe coolant that had gone through the engine already around the stator cover... I just checked and I think the coolant would be too hot for it to really cool the stator cover.
ok, lets look at it from another perspective, you take your stator
and you stick it in a 300 degree oven.
how long before the insulation breaks down and shorts to ground ?
a week ?
a month ?
a year ?
what if the insulation is rated for 500 degrees ?
where does that leave us with the heat idea, heat from
outside of the stator or heat from inside the stator.
do we know what the insulation temp rating is ?
do any of the manufacturers mention this ? I haven't seen it
so is the insulation on a stator made by Honda a better grade than Yamaha ?
Didn't honda have more regulator failures but fewer stator failures ?
we have a lot of data available to us, being able to quantify it is another story.
Here we are ............... stick on heat sinks from Jaycar, part No HH8580
Quote from: rm97 on September 30, 2012, 09:23:23 PM
Did George do any other modifications besides drilling a hole in the end of the bolt. If not I do not think his modification would have had any chance oil getting extra oil to the top half of the stator. When the engine is assembled that bolt is enclosed in a little circular area, making it impossible for the oil spray to hit the stator directly. That said I didn't see anything about indications of low oil pressure, so that could provide me with some reassurance to try my idea. . . .
Had the bolt drilled for oil flow but no other modifications to cool the stator. This was BTW the modification Yamaha prescribed for the Venture so it must have some merit.
http://web.ncf.ca/ag136/bolt.jpg
Don't really know if this helped because I sold the Vision.
Ron , the amount of oil in the stator case in the VX is higher than the Vision , IE, the drains are farther up in the centre case , I assume that this causes more oil to be thrown up upon the stator by the rotor, but not so much that there are excessive pumping loses.
A wild idea that I came up with , was to add a hose from a scoop , running to the oil filler , then add a fitting to the top of the stator case and run a hose to the air cleaned or a catch bottle, This would ventilate the crank case and circulate cooler air around the stator . This may cause too much oil migration out of the crank case , or there might be other problems, BUT it would cool the stator.
Do you guys think that the vision's water pump could handle adding an extra (small) coolant line running from the pump, through a small water jacket around the stator cover, and back to the radiator? Does that sound like a somewhat sane idea, or would I be robbing too much coolant flow from the cylinders? This would be more complicated, but not as risky as the oil sprayer idea. Please keep the ideas coming, I really like conversations like this!
Ron, I would think that the fact that the heat cycles from high to low has something to do with the failure. I purchased a rebuilt stator, so I could possibly get specs on the wire used on it. Someone could try running the bike with the stator (or flywheel magnet) installed, and without it installed, this would then tell you if the heat is generated by the stator.
If you suspect heat is the issue, taking an active assault with liquid cooling jackets may be beneficial but it seems needlessly complicated. You might get more bang for the buck going after the heat sink idea. Just my 2 cents. Since you asked :)
If I was keeping the engine on the motorcycle I would love to have the simplicity of the heat sink, but I'm not sure they will get enough air flow with my setup. That said, considering that these are all external mods, they could be changed around pretty easily. It might be worth at least trying the heat sinks first, it's not like they cost a lot.
I in my opinion, another alternator, outside the case, driven by toothed belt would make a big improvement, over the ell-cheep-o style of magnet we have. They did a nice job with the engine design, butt handed us a turd for a charging system.
On ebay 91-03 zx7 is the style that could easily be adapted
ok, I could see that, there is a lot of room under the flywheel.
that gives me an idea, what if you were to run an extra maybe half a quart of oil
in your engine. not enough to create problems but enough to
bring more oil up to the bottom of the stator...
there has to be a reason why some people haven't needed to replace a stator
and others need a new one every 2 years or so.
I like the scoop idea...
Quote from: Rick G on October 01, 2012, 03:48:08 PM
Ron , the amount of oil in the stator case in the VX is higher than the Vision , IE, the drains are farther up in the centre case , I assume that this causes more oil to be thrown up upon the stator by the rotor, but not so much that there are excessive pumping loses.
A wild idea that I came up with , was to add a hose from a scoop , running to the oil filler , then add a fitting to the top of the stator case and run a hose to the air cleaned or a catch bottle, This would ventilate the crank case and circulate cooler air around the stator . This may cause too much oil migration out of the crank case , or there might be other problems, BUT it would cool the stator.
In August, I met up with a forum member who was interested in a Bultaco I had. We got to talking about Visions (of course :D) It came out during that discussion he runs his 1/2 qt. over filled. He has been doing this for some time with no ill effects. Since then I've been doing the same.
I can't say if it helps with stator temps or not but I feel better knowing there is too much oil rather than not enough in the engine. Especially with the rash of rod bearing failures I've noticed of late.
Quote from: rm97 on October 01, 2012, 10:07:58 PM
It might be worth at least trying the heat sinks first, it's not like they cost a lot.
You may increase it's effectiveness with a dab of heat conductive goop like this (similar to the paste applied to the back of GM HEI modules):
http://www.ebay.com/itm/Thermal-Grease-Paste-Compound-Silicone-fr-CPU-Heat-Sink-/390166457118?hash=item5ad7bbab1e (http://www.ebay.com/itm/Thermal-Grease-Paste-Compound-Silicone-fr-CPU-Heat-Sink-/390166457118?hash=item5ad7bbab1e)
well see, now that is an interesting idea.
the book says 3.6 us capacity I'd say bumping to 4 qts would be a worth trying
and see what the long range effect is on the stator.
one downside I see is having more blowback oil in the air cleaner.
anything else ?
Quote from: Rikugun on October 02, 2012, 12:32:31 PM
In August, I met up with a forum member who was interested in a Bultaco I had. We got to talking about Visions (of course :D) It came out during that discussion he runs his 1/2 qt. over filled. He has been doing this for some time with no ill effects. Since then I've been doing the same.
I can't say if it helps with stator temps or not but I feel better knowing there is too much oil rather than not enough in the engine. Especially with the rash of rod bearing failures I've noticed of late.
!0 years ago , while in OR. i modified a clutch cover , so that it had a port to fit a thermocouple from an electric thermometer. I wanted to check engine oil temp. Maybe I should have put it on the stator case. I'd like to do it on the VX , but I have no spares for it.
Ron , if you add more oil , perhaps using a catch bottle would be better than the stock setup, into the air box.
Isn't V oil capacity supposed to be 2.9 qts?
Engine oil capacity:
-Periodic oil change, 2.4L (2.1 Imp qt, 2.5 US qt)
-With oil filter replacement, 2.7L ( 2.4 IMP qt, 2.9 US qt)
-Total amount (right after a rebuild), 3.4L ( 3 Imp qt, 3.6 US qt)
On the topic of cooling the stator... I have made some significant changes to the design of the dune buggy I'm powering with a Vision engine, and I now have lots of room for cooling fins. I could even run an external alternator as suggested, but I just bought a new stator, and I would have to deal with making an adapter to run a pulley off of the crank.
No, vibration does not cause stator failure in Visions. Heat does. The original Vision stator was built with epoxy that could not withstand the heat generated in the Vision. Yamaha later came up with a replacement stator with epoxy that could withstand higher temperatures. They were expensive and most people did not buy them. Do not under any circumstances buy a used Vision stator as it is probably a low temp model and well on its way to failure.
MOSFET, metal oxide switch field effect transistor. If the MOSFET does what its name says it does which is interrupt the stator current output instead of shunt it to ground, the stator may run cooler due to lower current in the windings. I may try one if(when?) my original '83 stator fails but I do have a higher temp OEM Yamaha stator as a replacement so I am not sure.
Quote from: admin on October 02, 2012, 01:38:45 PM
well see, now that is an interesting idea.
the book says 3.6 us capacity I'd say bumping to 4 qts would be a worth trying
and see what the long range effect is on the stator.
one downside I see is having more blowback oil in the air cleaner.
anything else ?
Quote from: Rikugun on October 02, 2012, 12:32:31 PM
In August, I met up with a forum member who was interested in a Bultaco I had. We got to talking about Visions (of course :D) It came out during that discussion he runs his 1/2 qt. over filled. He has been doing this for some time with no ill effects. Since then I've been doing the same.
I can't say if it helps with stator temps or not but I feel better knowing there is too much oil rather than not enough in the engine. Especially with the rash of rod bearing failures I've noticed of late.
Hmmm... I've always filled mine with 3 quarts at each change.
David
Mine is full at just under 3 qts. and my stator is original.
Between Walt and David it is beginning to sound like less oil in the crank case is better for the stator. This is a puzzlement. ???
well actually no, not that surprising because I wouldn't expect anyone intentionally
overfilling their bike and so we don't have any accurate data yet.
we do agree on heat being the problem but its not that obvious.
the heat is generated electrically, compounded by engine heat to reach the melting point.
I asked the question that hasn't been answered directly yet.
how long in a 300 degree oven can you bake a stator before it fails.
if the coatings are good quality with a high enough temp rating,all things being equal,
I'd say the answer is forever.
if it is marginal along with resistance from a lousy battery or a failing plug connector
the answer is not very long at all.
one thing to think about is that the ignition pickups sit right next to the stator and are
exposed to the same environment, we aren't having many of those fail.
what would be nice if we had a way to determine if the regulator was malfunctioning
enough to overheat the stator...
Walt are you also running a stock regulator ?
QuoteBetween Walt and David it is beginning to sound like less oil in the crank case is better for the stator.
Two data points does not make a thorough study make. ;D By that criteria the gentleman I referenced and myself both running 1/2 qt. heavy proves it works! I think the whole point of this discussion is a few have had long lived stators but no clear pattern has been established to show what the right ingredients are for success. And just to be clear I'm not recommending anyone overfill their crankcase although I will say a little too much is always better than not quite enough! ;) :P
Ron your comment of cause and effect as it relates to R/R is important. I've been struck by accounts of members installing stators (often used) every several thousand miles but sticking with the same regulator. Another fun game is one component goes bad and is replaced only to have the other fail some time later. Unbeknownst to you it's lifespan has been gutted as a result of the added stress placed upon it by the failing of the first component. You play this game for a few seasons alternating between replacing one then the other.... you get the idea. :'( I don't pretend to be trained in electronics but have always felt that one bad component can effect the other parts of the system. I'm sure the up front $ factor of replacing 2 expensive components is an issue but I'm at the point now that replacing one without the other can cost more in the long run.
Along the same lines is the question of battery condition. Some hang on to a failing battery by charging while not in use and relying on a higher than normal charge rate while riding. To me this puts undue stress on the charging components. Now here is where a "heated" debate on heat ensues....shunting vs not, high draw halogen bulbs helping or not, heat generated and how much when charging or not , blah, blah, blah. etc. etc. Bake a pie eat a pie. I say if the battery won't hold a charge, replace it. :laugh:
Walt's R/R may be stock with a PC fan? Others with a factory R/R sans fan still have good success while others not so much. Same with factory stators - a few have great success while most don't. When it comes to charging system woes there are so many variables at play, a definitive answer may never had. It's still good to have the discussion and interesting theories are suggested.
heh, exactly.
I do want to throw a couple more items into the mix.
for guys that have had long lived stators.
1. how long is the average trip you take on the bike?
2. do you typically park it on the side or center stand?
and just for the fun of it, lets make our own damn stators,
here is a stator winding machine for sale, anyone interested ?
http://www.alibaba.com/product-gs/510097629/2012hot_sale_motor_Stator_winding_machine.html
:D ;D :o ;D :D
HAH!!! And it's in China yet. Something tells me that could be an expensive proposition. Did you notice method of payment listed money gram, etc? No mention of bank wire transfer or other safer methods.
Some people have wound stators by hand (on this forum about 8 or 10 years ago , with good results. Ihahve the wire and the information some where. Its not all that hard . Some counted the number of turns of wire removed and some measured the length of removed wire. Lots of pics are needed while removing the old wire to get the pattern right. As i said , I have the docs on it if anyone wants to try.
If I was going to wind my own stator, I would try to come up with a special low performance wind. We don't need as high of out-put as these make now. One time, Dwight, out-put tested mike bike, he showed me, it was putting out 20 amps, at 4000 rpm. I am pretty sure around half that would be enough.
Quote from: admin on October 04, 2012, 12:43:46 AM
how long in a 300 degree oven can you bake a stator before it fails.
If only the vision internals could be subjected to a steady state 300*. In the real world it undergoes frequent heat cycling, which itself can be very damaging. And if you're assuming 300* surface temperature from your readings that doesn't speak to the internal coil temperature of a fully loaded stator.
I'd bet that finning the whole case, would make a big difference. Just think how important the finns on the r/r are.
The three I had fail seemed to be heat related, once they get to crisp, the crummy varnish insulation on the windings break down and the wire shorts to ground.
If I was going to wind one, I would use wire with some high-temperature insulation, e.g. teflon, ceramic.
http://www.phoenixwireinc.com/ptfe-wire.html
http://www.ceramawire.com/applications.shtml
The teflon is rated at 260 deg C and the ceramic at 1100 deg C. Either should be good enough.
If you're going to all the trouble of winding the thing, it doesn't make sense to reuse the same varnish insulation technology that has failed repeatedly in this environment.
The question I always ask myself is, having knowledge of the stator heat failure problem, why didn't Yamaha do this?
Quote from: supervision on October 06, 2012, 09:59:57 AM
I'd bet that finning the whole case, would make a big difference. Just think how important the finns on the r/r are.
That is basically what I'm going to try. I plan to cast an aluminum circle with fins, to completely cover the circular area on the stator cover. The fins will bolt on where the cover that says Yamaha on it usually does. I'm also going to try to get the fins to conform to the curvature of the cover, and maybe I will even use some of that heat conductive grease suggested. Since I'm not worried about my foot having to fit next to, or behind the cover, the fins can be about as big as I want them to be.
Why didn't Yamaha improve the insulation heat risistance? They did! Read my first post on this.
Quote from: Walt_M. on October 06, 2012, 06:09:07 PM
Why didn't Yamaha improve the insulation heat resistance? They did! Read my first post on this.
I bought a stock Yamaha replacement stator in '89 and '94 and they both failed, so it does not appear there was any better heat resistance in later parts. Mine failed like clockwork, every 25000 km, 5 years.
Most of my driving has been "around town" at less than 60mph for short distances and a lot of sitting at traffic lights. I have a digital thermostat and rarely get dangerously hot. I'll occasionally get out and do some longer riding with highway but that has been rare since I started my clinical rotations.
I also use the sidestand almost exclusively lately.
A lot of the talk begs the question, "what causes the heat buildup?" Is it the stator internally overheating and the epoxy breaking down causing a short? Is it poor heat dissipation of the Vision motor causing the stator to overheat which in turn causes the breakdown? A combination of the two? The list goes on....
What would be interesting would be for one of the guys with chronic stator problems to periodically remove the side cover and look at the stator to see what kind of condition its in.... time consuming, yes... either that or sombody CNC an acrylic sidecover so we can look at our stators and see whats going on.
David
Quote from: George R. Young on October 07, 2012, 09:21:37 AM
I bought a stock Yamaha replacement stator in '89 and '94 and they both failed, so it does not appear there was any better heat resistance in later parts. Mine failed like clockwork, every 25000 km, 5 years.
Did you re-use the same R/R both times?
I have 106,000 klm on our 83 with the same stator,most of my driving is crossing North America, on the earlier 82 Hannigan Faired Vision I had 78,000 klm with three stator failures -this was a mixture of long distance and stop and go traffic.
Other than soldering all charging related wire connections, my biggest change is Synthetic oil. I have a laser thermometer and pointing it at the engine stator cover I have noticed a temperature reduction of 8 to 12 degrees.
Interesting thoughts about vibration but I would discount it unless the stator mount Hdw was loose,old chev engines had a form of scoop on each rod cap which flung oil around the crankshaaft area for lubrication.A friend of mine rebuilt one in the late 50's and didn't install them .... Seized solid !!
My thoughts
Cheers Ken S.
That was Chevy;s old "dipper rod 6 . If the oil was bit low and you hot rodded it around right hand corners, all the oil would be thrown up the side of the block and starve it for oil, then BANG went a rod or two.
Hey Kenny,
Any chance you spectated at the WSB races at Brainerd back when they ran there. That was the only place I ever saw a Vision with a Hannigan on it. Was it yours?
Jeff
Quote from: Rikugun on October 07, 2012, 09:00:20 PM
Quote from: George R. Young on October 07, 2012, 09:21:37 AM
I bought a stock Yamaha replacement stator in '89 and '94 and they both failed, so it does not appear there was any better heat resistance in later parts. Mine failed like clockwork, every 25000 km, 5 years.
Did you re-use the same R/R both times?
Yes and it worked fine. The stator is approximately a constant current device. The purpose of the R/R is to change from AC to DC and to dissipate the excess current produced by the stator as heat. The R/R in my bike delivered DC and limited the output voltage to about 14.5 volts to keep the battery happy.
The fundamental problem is that with this R/R design, the stator is delivering full output all the time, heating the wire insulation to crispy, with resultant insulation failure.
I can think of two ways around this.
1) Different R/R design which only draws current from the stator as needed. Haven't seen one like this for the Vision yet. I have this type of operation on my Concours, and had it on my Yamaha RD350, and Bridgestone 350GTR, because they have excited field alternators instead of the permanent magnet/full output all the time kind in the Vision.
2) Stator rewind with teflon insulation, the stator still puts out full current all the time, the wire still gets hot, but the insulation doesn't break down. Haven't seen this either.
There are two problems with excited field charging systems, #1 is cost , its a much more expensive system. #2 room , its a much larger system and would result in a very large laft hand case . If it were mounted on the top of the trans , behind the cylinders there might be room. Its a dry system as far as I have seen , IE, does not run in an oil bath.
ok, well at this point it seems our main goal is to eliminate or reduce the amount of time
and money that we need to spend on the charging system, period.
while we don't have 100% definitive answers on why the failures happen so often on many if not most of our bikes,
we do know that there are tens of thousands of other bikes that use this charging system.
let me repeat that, tens of thousands of other bikes use this charging system.
we know they all also have various problems whether it is the stator, the reg-rec or the melting plug syndrome,
they are all having issues.
What we need to do is come up with a list of the steps that should keep the problems to a minimum.
1. make sure your battery is in tip-top shape, replace it every 3-4 years.
the reality is that this may be the elephant in the room.
2. pitch the stock regulator and put a larger, heavier duty unit, ie newer style mosfet.
on a side note: has anyone looked closely at the stock regulator harness ?
are those wires aluminum ?
3. ditch the stator plug and solder those wires permanently.
4. what else... run a honda stator ? :'(
comments ?
Hi Jeff,
I haven't been to the races at Brainerd, but had travelled from B.C. to Windsor Ont. once across Canada and the next time across Hwy 2 from Grand Forks to Minot and Colville, somewhere around 83-85 or near that year.
Hey Ron don't forget about the Synthetic Oil. ;)
Cheers Ken S.
Ricks Electrics would agree with you Ron...
"Heat and vibration break down the insulation on the copper wire inside the rotor, resulting in a "short" of the current from one coil to the next. This prevents the electro-magnetic rotor from providing sufficient magnetic strength to produce a strong charge in the stator.
A failed rotor can also result in a secondary problem. When the internal "short" occurs, the resistance in the rotor goes down and current flow increases. This puts a heavy load on the rectifier/regulator and may burn out the regulator unit. Simply replacing the rectifier/regulator because it looks bad will yield the same results – the bad rotor will continue to burn out new rectifier/regulators. When the rotor fails, always replace the rectifier/regulator to prevent future problems."
They also note that their rebuilt Honda rotors are the company's biggest seller
Quote from: roro on October 11, 2012, 06:35:13 AM
. . . A failed rotor can also result in a secondary problem. When the internal "short" occurs, the resistance in the rotor goes down and current flow increases. This puts a heavy load on the rectifier/regulator and may burn out the regulator unit. Simply replacing the rectifier/regulator because it looks bad will yield the same results – the bad rotor will continue to burn out new rectifier/regulators. When the rotor fails, always replace the rectifier/regulator to prevent future problems." . . .
This part gives me problems. The stator puts out a constant current, about 20 Amps. If there is an inter-winding short, some of this current is shunted internally, and LESS is delivered to the regulator/battery/bike load. If the short is from winding to ground, the output current drops drastically.
In neither case would there be additional load or stress on the regulator.
I think this claim is because they are in the business of selling stators AND regulators.
The only way a stator could harm a regulator is if magically all the magnets became stronger and the output increased.
There is no way I know of that a faulty regulator can harm a stator. If it fails open, the DC voltage would go up and the lights may blow and the battery may boil, but the stator doesn't care. Even if it becomes a short circuit, the stator is quite happy delivering its 20A into a short circuit, but the battery will stop charging and eventually the lights will dim and the bike will stop.
The stator failures and the R/R failures are in my opinion independent.
George I believe you are right on all counts
notice however the website refers to rotor not stater they are talking about the type of router that is controlled by the regulator not the permanent magnet type of rotor if we have
In a correctly functioning charging system, stator output voltages range from a diode drop below ground to a diode drop above battery voltage. When a stator winding shorts to ground, stator voltages are directly referenced to ground at the short. This causes voltages to alternate above and below ground in at least two of the stator output wires. IF the regulator semiconductors were not adequately specified for the reverse voltage caused by this abnormal operating condition, I believe it would be possible for a shorted to ground stator to damage a regulator.
Last year there was a lot of talk about Mosfet R/R's from R1's and the hope fitting that these would contribute to the longer life of stators. For those who have gone down this route, is there any evidence that there has there been an improvement or otherwise?
In my correspondence with the fellow (d'Ecosse) who wrote the MOSFET article on the eviltwinsbk site, he stated he had never seen a failed MOSFET RR unit. I was having difficulty testing the ones I had bought and they didn't pass the test for our original RR units. I first thought they were no good and contacted him for more information only to learn they don't test the same way. Actually, I don't know how to test a MOSFET unit other than plugging it in and trying it. So far all the ones I have had work well. It seems they are significantly more robust than the silicon gate type that came with our bikes.
The MOSFET units with two 'pig tails' like the original RR unit from the XZ come from Honda CBR600RR '05 and later and CBR1000 '07 and later I think. There may be some from other makes and models that fit this description but these are the ones I am familiar with. The pig tail configuration makes the adaptation to the XZ much easier than using some of the many other MOSFET RR units that only have receptacles in them which require you to make up wires and plugs for them.
Quote from: pinholenz on October 15, 2012, 06:38:38 PM
Last year there was a lot of talk about Mosfet R/R's from R1's and the hope fitting that these would contribute to the longer life of stators. For those who have gone down this route, is there any evidence that there has there been an improvement or otherwise?
When I got my 82 it had 6k miles and a faulty original stator. Around the same I bought a parts bike with 16k and it had a replacement stator that was on it's way to the grave and only lasted several thousand miles. Unfortunately I have no way to know if that replacement was it's first or how many miles were on it.
I replaced the stator with a new one and the R/R with a low miles used MOSFET from a Honda. The R/R runs relatively cool even mounted in the stock position. The stator is still going strong but I've only accumulated maybe 8k since then. A success to me will be in excess of 50k so I'll keep you posted. :P :)
Regarding fret nut's comment regarding lack of failed MOSFET units it will be interesting to see if that changes over time. There are significantly less units in service compared to "conventional" types so the incidence of failure is not surprisingly low.
ok from what i kno... wire connections corrode under the right conditions. aggreed?? (im going to assume you all agree)
SO with that said... corrosion=resistance; resistance=amp-draw; amp-draw=heat; heat=toasted stator
someone correct me if im wrong.. :o
Resistance reduces current flow, whatever current does flow through a resistive connection (corrosion) will cause heat to be generated. (Power =IxE) IxE = heat which equals toasted resistive connection. BDC
Interesting to see the old topics are still coming up :). Heat is the major problem as has been discussed, exactly why it appears to be more of a problem on the XZ than other bikes using the simple permanent magnet 3 phase stator is unsure. The core problem is the stator produces full power (load current) all the time, the faster it spins the higher the AC voltage output. The shunt regulator converts this to DC and the passes the required current to the battery to keep it charged, the rest of the current is dumped (shunted via a resistor) to ground.
From memory the stator produces 20Amps, so if only 5amps is required at the time to top up the battery and run the ignition the other 15 is shunted to ground which makes the regulator rectifier (R/R) very hot too. So the basic issue is the stator and R/R run at full load capacity ALL THE TIME and get very hot due to this. A fully controlled system would reduce the output voltage of the stator as the revs increase and as the load requirement decreases so both the stator and R/R only handle the minimum load required by the bike, hence running cooler. Unfortunately due to simplicity of using permanent magnets on the fly wheel round the stator we can't control the magnetic field so the fast it spins the more voltage/current we get. Alternators like in cars don't use permanent magnetics they have a field winding which produces the rotating magnetic field and a feedback system controls the voltage to this to reduce the output of the stator as required.
Note also a faulty R/R, for example one with shorted retectifier diodes will cook a stator as well because shorting one of the phase windings will cause as much current as it will produce to flow through it heating it up even more. Diodes break down due to heat so it's also possible for these shorts to occur only when above a particular temperature and when it cools down it's ok again. So it's possible to have a faulty R/R under load but fine when you test it with a multimeter. I know of auto electrical shops that have replaced a stator only to have the replacement ones go due to a apparently good R/R. So it is a good idea to replace both at the same time unless you have the right equipment to test them properly.
Very interesting to read the post about the MOSFET R/R on eviltwinsbk.com and that they run very cool. This is possibly because rather than shunting excess load to ground it disconnects from the 3 phase windings kind of switching the load on and off. There was a guy on the list some time ago looking at this but the problem was large back EMF and voltage spikes on connection/disconnect which the electronics couldn't handle. It's also possible that it's still working as a shunt system and because of using MOSFETs which are more efficient at switching don't get as hot. Think I need to read up more on how these newer R/R work.
Anyway this all comes down to needing to take temperature measurements of the stator winding. That way we can see just how hot they get and whether a little more oil, an oil cooler or in fact using a MOSFET R/R rather than the old style really does make a difference to stator temperature. I do have a stator I rewound and put a thermocouple in it with the aim of taking measurements I guess I need to find it and get the testing done :D
Quote from: kiwibum on October 23, 2012, 06:05:19 AM
. . . Note also a faulty R/R, for example one with shorted retectifier diodes will cook a stator as well because shorting one of the phase windings will cause as much current as it will produce to flow through it heating it up even more. Diodes break down due to heat so it's also possible for these shorts to occur only when above a particular temperature and when it cools down it's ok again. So it's possible to have a faulty R/R under load but fine when you test it with a multimeter. I know of auto electrical shops that have replaced a stator only to have the replacement ones go due to a apparently good R/R. So it is a good idea to replace both at the same time unless you have the right equipment to test them properly. . .
I have a problem with this part.
The AC output voltage of the stator rises with RPM. The stator is essentially an inductor so it's internal impedance also goes up with RPM (i.e. frequency). The output current is therefore approximately CONSTANT, i.e. voltage divided by impedance.
The thing puts out about 20A all the time (at any engine speed useful for riding). It's just as happy delivering its 20A into a shorted diode or the normal bike load. I wouldn't change a Reg/Rect if it's producing DC voltage and clamping it around 14.5V.
I have 2 engines on the bench right now and have been studying how it's all designed. I have an off the wall idea:
the center of the stator frame bolts to the case cover. The poles the wire is actually wrapped around touch nothing. Clearances around the poles are very tight and they cannot be 'bathed in oil' in the current set up. They get oil mist at the most.
The idea of cooling fins on the outside probably wouldn't hurt, but may be ineffective at cooling the poles much...
the idea of drilling the bolt to spray oil a-la Venture, would only result in the Yamaha name badge getting sprayed with oil from the inside.
Because of the magnet placement in the rotor there is only one spot to drill the rotor/ crank to route a spray of oil on the stator, and that's in line with the key, so you couldn't seal the passage, so that idea is out.
I looked at the cover, rotor and stator for a long time & really only see one way to access the poles, & everyone is going to think its nuts...
If the cover ( or a spare) is surgically drilled/cut in segments around the poles, cooling air could be introduced almost directly onto the poles, probably with a low profile scoop and a foam air filter.
just brainstorming...
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The idea is great Lucky, the problem is the crankcase pressure. It would blow out the vents you put in the case and it would be hard to filter the oil vapour out. I like your oil-cooling idea as one of the best ways to keep crankcase temperatures down.
I thought about that, I haven't done it in a while but you can remove the button over the clutch adjuster on the right case while the engine is running. There is a little pressure but not so much that you can't thread the button back on. Not bad really...
My thought about this situation is that as long as the scoop is designed properly it might work. It would have to be sealed well to the case, there would need to be some small drain back holes inside, and a foam filter and baffling used for oil deprecation. The filter would need to be set back into the scoop a bit.
I'm half tempted to cut up some cases to experiment but I think a few of you would freak....
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Quote from: Lucky on October 24, 2012, 02:10:51 PM
I thought about that, I haven't done it in a while but you can remove the button over the clutch adjuster on the right case while the engine is running. There is a little pressure but not so much that you can't thread the button back on. Not bad really...
Is that at idle or under load at cruise RPM?
It is interesting but I'd be fearfull of riding in the rain with standing water or just going through puddles for that matter. The chances of foriegn matter being scooped into the engine just seems like a real pitfall. At the very least it seems the engine would soon become an oily mess. External fins seems like a better compromise. Just my 2 cents... :D
Yep that would be a problem. There might be a better way to introduce cooling air (or oil?) such as a snorkel. I'm just presenting possibilities. It would be physically possible to access the poles on the stator. Direct access introduces the potential for an outside the box idea...
Maybe a closed loop where the oil mist is forced up a tube by crankcase pressure* and dumps back in at the oil fill. If I could sketch this out on paper it might make a little sense. The tube, being in clean air might cool the air/oil mist some...
I had the plug off at idle, at speed it might blow out with some force. Maybe we simply need to build a crankcase air cooler lol
Again, just brainstorming...
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Lucky, you will notice in the first page, I suggested this. It was the result of a conversation with Don Minor in 2008.
If we introduce air into the filler , from a hose connected to a small scoop, located above the radiator and a second hose running from the rear of the alternator cover , ending in a catch bottle, located up under the seat, it would cool the stator. The high location of the intake and exhaust , along with the catch bottle "should " prevent oil migration and loss. Any one want to try it?
Cooling jacket fashioned onto the stator housing. Small electric pump moves coolent through jacket to small, in air flow, radiator.
Rick that's where I got the idea from the first time you mentioned it although I didn't go back & reread your post. The stator is so isolated inside the rotor that I'm thinking the air may not be much cooler by the time it reaches the poles.
I do see the advantage of the intake & drain back being up high. I think for this to work along the lines I'm thinking it would be pretty ugly huh? :)
QBS, I'm thinking along the lines of cooling the poles more directly only because I'd imagine it to be more efficient. Honestly though I think a higher quality stator with more heat tolerant insulation along with better connectors, the newer style r/r and a cleaned up electrical system are really
the way to go.
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There is a heavier duty stator from one of the early XV's that fits. Can't recall the exact model just now but I have offered one up and it does fit and they are available new.......
Opinion has it that the XV unit will last due to meatier construction and is rated at higher amps.
Quote from: George R. Young on October 23, 2012, 10:33:28 AM
Quote from: kiwibum on October 23, 2012, 06:05:19 AM
. . . Note also a faulty R/R, for example one with shorted retectifier diodes will cook a stator as well because shorting one of the phase windings will cause as much current as it will produce to flow through it heating it up even more. Diodes break down due to heat so it's also possible for these shorts to occur only when above a particular temperature and when it cools down it's ok again. So it's possible to have a faulty R/R under load but fine when you test it with a multimeter. I know of auto electrical shops that have replaced a stator only to have the replacement ones go due to a apparently good R/R. So it is a good idea to replace both at the same time unless you have the right equipment to test them properly. . .
I have a problem with this part.
The AC output voltage of the stator rises with RPM. The stator is essentially an inductor so it's internal impedance also goes up with RPM (i.e. frequency). The output current is therefore approximately CONSTANT, i.e. voltage divided by impedance.
The thing puts out about 20A all the time (at any engine speed useful for riding). It's just as happy delivering its 20A into a shorted diode or the normal bike load. I wouldn't change a Reg/Rect if it's producing DC voltage and clamping it around 14.5V.
Yes, the impedance goes up with frequency, therefore the voltage must be increasing as well for the current to remain constant otherwise the current would drop off. Here is the output graph of the AC generator in the service manual.
(https://lh6.googleusercontent.com/-YtKbRoPAR3E/UIjFLm9X_9I/AAAAAAAAAAY/TKDesz0dir0/s640/XZ550_AC_generator_graph.jpg)
This is with a load of 280watts. If a diode shorts this will decrease the load resistance which will increase the current drawn from the phase the short is on. Extending this further if one phase has a complete short across it the impedance of the coil is the only limit on the current so more than 20amps will flow I think. I think the 20amps is average and the peaks are higher because the phases are being shorted to ground to regulate the output voltage. The stator will get hotter the higher the RPM due to the longer periods the phases are shorted to ground as the AC voltage is higher.
Because it's a 3 phase shunted system it will still produce DC voltage regulated to 14.5V with a faulty diode or shunt transistor. Remember the phases are being clamped to ground to regulate the output voltage, if one phase is shorted to ground permanently the other two phases will be clamped less to keep the output voltage at the correct voltage. The average DC output will still be 14.5V but the AC ripple on it will be from two phases rather than three, so you wont see it on a multimeter only measuring with an oscilloscope. Mean while the stator is cooking because the peak current is flowing in the shorted phase.
The stators I've pulled apart have all been black and charred like this one below.
(https://lh4.googleusercontent.com/-FfZS2drKT2E/UIkAX-dL-kI/AAAAAAAAABs/sNXZrRvSktw/s640/PICT0031.JPG)
On this one the final problem was cased by vibration with the insulation breaking down and the wire rubbing on the stator poll. However this was allowed to happen because the encapsulating glue holding the coils on the polls breaking down from excessive heat allowing everything to move round and rub together. This is really a harsh environment for an electrical component to operate, cycling heat loads from cold to very hot (from the engine as well as the electrical load), constant varying high vibration and oil.
(https://lh6.googleusercontent.com/-4x2qOy2viF0/UIj-tDDNUxI/AAAAAAAAABs/Ky3SfA9Mnkc/s640/faulty-polls.jpg)
Reading more about the MOSFET R/R they are still shunt circuits operating the same as the original SCR based ones so the stator will still have the same high load on it all the time. So the stator will still run hot but it looks like the MOSFET R/R are much more reliable therefore less like to fail or partly fail and take the stator out. Interesting reading other bike sites that are reporting doing the MOSFET upgrade, plenty of other bike models with the 3-phase permanent magnet stator like the XZ have the same stator failures.
Ultimately I feel the solution to keeping the stator cooler will be an electronic one that controls the output of the stator to provide the minimum power needed for the bike at all times rather than the current system that pulls full power from it all the time. So I think part of the problem is it's delivering 20amps all the time but can't quite cope with the heat involved when you include heating from the engine too. And yes if we could keep it cooler by some means it probably will cope at 20amps but it's in a difficult place to keep cool. Once I get the bikes out of storage I'll be in a better position to measure the temps and see if different R/R, heat sinks on case etc do make the difference we need.
Sorry for the long post, have been thinking about the bikes too much lately and would like to help solve some of these problems. Much more interesting that what I'm currently working on. Looking at the photos I have of the stator rebuild it's been almost six years since I've had the bikes out :'(
No need to apologize for the lengthy post. I appreciate the time and thought that went into it. It's also nice to see someone addressing the core cause rather than trying bandaid methods to control the symptoms. Of course attacking on both fronts increases the chances for a workable solution but I'd rather see one that doesn't add unnecessary complexity. An electronic fix seems more elegant than some of the other methods suggested. Hope to hear more from your investigations. :)
Treedragon, the XV stator seems to be the simplest solution in that it only requires choosing the correct replacement when the time comes. :D I'm a bit confused by your post though... Do you have one in your bike but just don't recall the model it came from? If there is a more robust stator from an older model I guess supply comes into play. If new production for replacements for that model exist, one can only hope the same quality materials are being used to give the same performance/life expectancy.
Check this out, Google magneti marelli catalogue 2011 This has really high quality stuff. they show a permeant mag alt for MOTOGP. They show how it is done, first spinning the magnet in the center , not around the outside. It also show size and all.
The cut in speed is 2,500 rpm, and the thing only makes 15 amp at 4,500, max out at 22amp past 6,000. The reason I thing this would run cooler is the way the winding is not captured by the magnet, it is in the center of the winding.
Rikugun
no I don't have one in my bike but I did have one in my hand.
They are available aftermarket new around NZ$200 and something as I recall, my current situation doesn't run to having any spare coin to spend so I "make do" in this case I have one out of a CX Honda I think with the excess wires clipped. There was only one XV model they came out on and unfortunately I seem to have a memory like a sieve with a hole in it just now so details are sparse.
Who knows what the future might bring so I will relook should this one cook ;D
Quote from: supervision on October 25, 2012, 11:14:35 AM
The cut in speed is 2,500 rpm, and the thing only makes 15 amp at 4,500, max out at 22amp past 6,000. The reason I thing this would run cooler is the way the winding is not captured by the magnet, it is in the center of the winding.
I think the requirement of higher RPM (other than GP stuff revs high anyway) is because the rotor is in the centre and a small diameter. It will have to turn faster to get the same surface speed (magnetic flux cutting the stator coils) that if it was on the outside and larger diameter like the XZ.
And yes having the flywheel enclose the stator will definitely hold the heat in. This makes me wonder if cutting a diagonal slot between the magnets or even drilling holes through the flywheel to enable more air movement round the stator as it spins would help with cooling. Would lighten the flywheel a little which wouldn't be a big issue but it would have to be balanced correctly.
Kiwi, did you see the pictures of the stators, with the center mag?
Quote from: supervision on October 25, 2012, 06:29:14 PM
Kiwi, did you see the pictures of the stators, with the center mag?
Yes I did, that's what my last reply was about. These wouldn't work on the XZ because the flywheel on the XZ is the rotor, the mass of the centre mag on the magneti marelli one would be too small I think. It's a great idea to have the stator on the outside like that to get better cooling which made me think about what could be done to the flywheel on the XZ to help cool the stator windings.
ah kiwi you stole my idea..., great minds think alike ? :D
the idea is that you drill some cooling airflow holes in the flywheel, possibly replace the magnet
and lighten the flywheel at the same time.
I like the design idea of a heavy flywheel in the way that the vision was built but in the real
world, I think I prefer the rpms to rise and especially drop quicker and dump some of that effect.
years ago I didn't mind it but now I feel like it sometimes gets in the way.
I'm (Still) in the camp that says playing with cooling the stator via fins and oil coolers is a fun science project
but the real problem is electrical and needs to be addressed and ultimately solved that way.
I'm currently running a used honda vt500 stator and mosfet reg/rec hoping I'll get 10 years out of it... :-\
I have one of those virago stators that will fit if you really must do it but, if you have any crank thrust clearance
issues with your vision motor you will have a crankcase full of cast iron filings ( not good )
btw I am selling my extra virago stator for 45 plus shipping if anyone is interested. 8)
to quote Doc Brown " This sucker is electrical"
Quote from: kiwibum on October 25, 2012, 06:10:33 PM
And yes having the flywheel enclose the stator will definitely hold the heat in. This makes me wonder if cutting a diagonal slot between the magnets or even drilling holes through the flywheel to enable more air movement round the stator as it spins would help with cooling. Would lighten the flywheel a little which wouldn't be a big issue but it would have to be balanced correctly.
Quote from: admin on October 26, 2012, 01:06:25 AM
ah kiwi you stole my idea..., great minds think alike ? :D
the idea is that you drill some cooling airflow holes in the flywheel, possibly replace the magnet
and lighten the flywheel at the same time.
mmm... Maybe this would be a nice way of lightening a XZ400 flywheel that little be more and enabling some cooling for the stator as well. Lots of things to test and try.
Wouldn't the magnets break? I've never tried to drill a magnet.
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yes they would break, it would probably be a mess.
in my mind I envisioned (pun intended) pulling out the magnet and having
a machine shop drill and lighten the flywheel it along with finding a way to use those
new rare earth magnets that are super powerful.
I remember reading something about how they added weight to the flywheel intentionally
at some point in the process and so maybe along the way the engine builders got a
little too crazy with adding the extra flywheel weight and goofed up the original design
that allowed for more clearance or whatever.
of course at this point we are now in cost prohibitive land because the cost for re engineering
the flywheel wouldnt be too cheap.
but lets just say we wanted to do this on the cheap, you could drill two or four opposing
holes in the flywheel, inside, away from the magnet, if you were careful enough and measured
pretty accurately you could probably do it well enough to not upset the balance of the thing
you'd get some airflow in the process, possibly enough to make a difference. ( lots of if's here )
Supervision, very cool on the magnetti marelli stuff, man ya gotta love those Italians, a great idea
swapping the location of the rotor and stator for cooling. obviously why the Japanese are better at copying
than innovating but I digress.
if you could swap out the stator and flywheel locations then we probably wouldn't be here... 8)
Quote from: admin on October 26, 2012, 09:57:16 AM
but lets just say we wanted to do this on the cheap, you could drill two or four opposing
holes in the flywheel, inside, away from the magnet, if you were careful enough and measured
pretty accurately you could probably do it well enough to not upset the balance of the thing
you'd get some airflow in the process, possibly enough to make a difference. ( lots of if's here )
That's what I had envisioned, carefully drilling to miss the magnets. Can't remember what the flywheel is like on inside now but there should be space between the magnets and enough to drill between. I assume the holes would want to be on an angle to help scoop air in or out (another issue which way to angle them) rather than perpendicular to the outside.
If you could dry the rotor you might be able to set up an oil spray on the stator poles. You have an oil passage in the crank that feeds the starter clutch gear. The trick would be that it would need to be drilled vertically thought the side of the rotor (near where the clutch bolts go) lining up with the oil passage in the crank, then intercept that passage horizontally at the level of the poles.very exacting drilling
If there was a spot to do it.
If the resulting loss of oil pressure is ok.
If centrifugal force didn't just throw the oil onto the inside of the rotor...
Might work.
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Drill the rotor, not dry it lol
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That's a hoot about the Magnetti Marreli electrical equipment. it looks great ! Its afar cry from their stuff used in 60's Duc's it was awful back then!
I think that drawing heat away from the stator is better accomplished with direct heat conduction through the case and to the heat sink idea on the outside of the case. Probably better contact of the stator to the case could be fashioned for more efficiency in conducting the heat to a sink.
Of the three stators I have one is crispy and crumbly with some loose outer winds on a few coils because the epoxy has crumbled away. The other two have smooth epoxy but one is black and the other is slightly more brown but still rather dark color. The smooth epoxy stators test good but are on the way out judging by their coloration. I'll use them as long as they don't become crumbly. It seems obvious to me that heat has done the crumbly one in and is working on the other two, and that the windings becoming loose as the epoxy crumbles away allows the windings to vibrate and move about, which in turn can cause metal fatigue of the windings. That's the open and short of it, I think. ;)
So, MOSFET or other efficient regulator to help prevent heat build up, plus heat dissipation to keep the epoxy from falling apart should go a long way toward prolonging stator life.
Sorry to dredge up an old post, but someone said it's good to flog a dead horse for new perspectives etc.
A question I have regarding stator failures is what climate are most of the failed stators being ridden in, style of riding, duration. I suppose in most cases it's difficult to answer as many of our bikes have changed hands numerous times.
There has been talk of heat sinks and air cooling, oil cooling as well. I would like to add my theory.
What if a breather hole was drilled in the crankcase in a suitable position to catch a lot of oil splash from the crank. A hose routed to the stator cover with a fitting aimed at the top of the stator (where many think is lacking in cooling) providing at the least an oil mist/drip?
Would be a simple mod for only a couple of dollars.
A big part of the problem is that the stator is enclosed inside the flywheel and there isn't really a good way to get oil to it. Another problem is the oil that does get to it is already going to 200 degrees or there abouts. It would be alot better if the stator was in a sealed compartment from the engine. I also have an xs750 and the stator is sealed off from the engine and I don't see near as many stator problems with that model. The other thing is they run a demand system on those bikes and that has a lot to do with less stator burn ups. If our system could be converted over to a demand system then I think we would see alot better life out of the stators. I know it would take a different reg/rec, but not sure what else as electrical is not my forte. One thing that I think would help our stators is to use some of that heat sink paste that helps to conduct heat. If that was used between the stator and the sidecover it might help some with the heat. Whatever was used would have to be able to withstand the oily environment.
Jeff
Quote from: dingleberry on January 21, 2014, 03:59:39 PM
I would like to add my theory.
If we have to have a theory - here is mine
My feeling is the stator's working temperature thing is a bit of a red herring.
While it is impossible to know the heat rating of the wire used, the engine shouldn't be getting anywhere near as hot as the insulation rating - often 180
oC or 200
oC . If it was, we would be getting stator burnouts after a single hard ride, not after thousands or even tens of thousands of kilometers.
I've seen a whole bunch of XZ stators. They seem to be either uncharred (not to be confused with oil blackening) and working fine, or charred and failed - no in between. Yes, obviously heat cycles and vibration will cause degradation and damage, but these would show as localised black spots where mostly we are talking sudden and violent failure of the entire stator. I think we need to look elsewhere for the majority of failures.
I think the problem is the R/R.
When the R/R determines it is producing too much, then the SCR, dumps it back to earth. This stops the battery from boiling and bulbs from blowing, but the excess energy has to go somewhere, and that somewhere is the stator - which will heat up.
If there is a lot of current switching the SCR will overheat and fail. SCRs can fail while they are over temperature and return to being perfectly normal afterwards.
When the SCR fails, it will stop latching. It can do so in one of two ways - it will either send all current to the battery (and so it will boil, and bulbs will pop, or it will dump it ALL to the stator. The stator is not designed to handle this and will turn into a crispy critter.
If I am correct the problem can be addressed in a few ways.
1. Reduce failure of the R/R by increased ventilation and/or heat sink area OR switching to a less failure prone R/R (eg Mosfet)
2. Reduce R/R switching by consuming more power - ie High wattage lights always on - note that racers have real issues with burning stators as they typically only power the TCI - many will switch to series regulators which burn excess power rather than deliver back to stator
3. Place a power consuming device (ie high power bulb or large wire wound resistor and heat sink between the R/R and earth)
Do the SCR's ground stator windings to reduce rectifier output to a prescribed DC threshold? If so, what produces more heat in the R/R: 3(?) SCR's working hard with minimal load on the system or 6 diodes working hard with the addition of mega watt bulbs and/or resistors etc.
Jefferson - while the costly and complex excitable field alternators are a thing of the past (for bikes), the "make only what you need" scheme does offer some advantages. Unfortunately, converting an XZ to this charging system would be quite an engineering project. It would make fitting alternate carbs look like a walk in the park. :)
Quote from: Rikugun on January 22, 2014, 10:17:47 AM
Do the SCR's ground stator windings to reduce rectifier output to a prescribed DC threshold? If so, what produces more heat in the R/R: 3(?) SCR's working hard with minimal load on the system or 6 diodes working hard with the addition of mega watt bulbs and/or resistors etc.
As far as I can tell the 6 diodes will be busy generating heat regardless of the path the electricity is taking
The 1 or 3 SCRs (I should crack open one of my failed units) generating heat (mostly) only when they switch
Quote from: ProphetOfDoom on January 22, 2014, 01:19:55 PM
As far as I can tell the 6 diodes will be busy generating heat regardless of the path the electricity is taking
The 1 or 3 SCRs (I should crack open one of my failed units) generating heat (mostly) only when they switch
if you say so :)
Excited field alternators do not produce any current if the battery is dead (needs voltage to excite the field). They were not bad if the battery was in good health. My Honda 750s had them.
Quote from: Rikugun on January 22, 2014, 09:28:10 PM
if you say so :)
Well not because I say so, but because every schematic I've seen has the diodes on the stator side of the SCR :P
It's definitely heat. I recently refreshed my Venture Royale which has the drilled crank and while it lasts much longer than the Vision (about 100000km) it stills wears out (eventually). And the interesting thing is that it wears out in the same top high heat zone. I have gone through two original Venture stators and they were both toasting up in the upper 1/3 of the stator. All my Vision stators (3 now) toasted in the upper zone, so lower in the crankcase is definitely better for stators.
The Venture not only drills the crank but it has a tin cover (inserted in the sidecover) that allows the oil to fill it up and then it spills out onto the flywheel as an oil feed that baths the stator inside the flywheel. This can only be a cooling effect on the stator which is really isolated from the crankcase oil. When smaller flywheels were the norm and stators were on the outside they lasted forever. It's an unhealthy engine design for stators. Great for throttle roll-ons but bad for electrical.
Now if you could rotate your stator you could get a lot more use out of it. This is kind of tough though because of the wires that exit from the windings needing to move (never tried it). I have a Mosfet on an OEM stator for the last 10K and it should be due anytime so if I get another season it will be the most likely reason for doing so.
This is an oldie but goldie topic! Thanks Ron!
Quote from: ProphetOfDoom on January 22, 2014, 02:23:37 AM
If I am correct the problem can be addressed in a few ways.
1. Reduce failure of the R/R by increased ventilation and/or heat sink area OR switching to a less failure prone R/R (eg Mosfet)
2. Reduce R/R switching by consuming more power - ie High wattage lights always on - note that racers have real issues with burning stators as they typically only power the TCI - many will switch to series regulators which burn excess power rather than deliver back to stator
3. Place a power consuming device (ie high power bulb or large wire wound resistor and heat sink between the R/R and earth)
Maybe a zener diode like on the old brit bikes? Would that work as number 3 above?
I wonder how some stators in dry covers last so long?
Does anyone know the claimed OEM alternator wattage?
Referring back several weeks to the discussion of rectifier operation, when the battery is below the charge voltage, roughly 14 volts, the alternator output current flows through the 3 supply diodes, into the battery/loads and back to the stator through the 3 return diodes. When the battery is above the charge voltage, perhaps from being jumped by a running automobile, the output flows through the SCRs and back to the stator through the 3 return diodes. During usual operation, stator phase current flows through the supply diode until the SCR is triggered. Then the remainder of the current for that cycle flows through the SCR.
My best guess is that the most power is dissipated in the rectifier during normal operation. This is because the SCRs switch when phase currents are high.