Stator blows with annoying regularity? then read this

[vadasz1]

No I think Kenny S. is the luckiest SOB.  He past the 100,000km mark and still on the OE stator, if I recall correctly.

[QBS]

When I die and have my exit interview with The Lord, and if I'm allowed to speak, one of my first questions will be "What causes' V stators to fail often?".

I don't think the answer is down here.

[Lucky]

Well gee QBS, fat lot of good that'll do us, we'll still be stuck down here unless God has a good ISP, because your gonna have to let us know the answer.

[motoracer8]

Gentalmen of the forum, I deal with old British motorcycles quite a bit and I'm shure any of you that have been around motorcycles for awhile have heard many of the Lucas tails of woe. The Lucas AC systems worked just like the the system on the Vision with one exception, they did not use a regulator, but a rectifier and one or two Zener diodes in a heat sink to get rid of the heat, these systems were quite reliable, poor conections and cheep switches were the biggest probblems, but the main reason a stator would fail is not enough clearance between the stator and rotor magnets. Because of poor assembly quality and or crankshaft flex the rotor would touch a stator pole and local overheating would take out the stator. My point here is when you examine a failed stator make shure in look for any signs of the flywheel magnets touching the stator poles.

 Ken G.

[Brian Moffet]

But still, I am on my original stator close to 33kmiles. Maybe I'm the luckiest SOB out here?

Sorry Jason, at best you're the second luckiest...  (45,000 miles on original stator)  ;D

[inanecathode]

...inanecathode...You are oversimplifying the system and how it works.   Yes the system is always working and excited. BUT NOT AT MAX power.Ours does not get near max till 3000rpm or so. Thus not getting your "max  AC voltage" till then.  And that's converted to about 250w 14vdc in our system. ALL A RESULT OF RPM AND AVAILABLE GERERATED FLUX. FLUX IS ALWAYS LOWER AT LOWER RPM. And that's where the R/R comes in. As we know, to change AC to DC and dump what's not needed. A.K.A. TO take what's available and change it into what we need. SAY IT AGAIN,  "max is not available all the time." Jeeeeezzzzz basic law of generator design...More rpm = more available power.If you exceed the system's available output by excessive draw, you are going to have problems. Look in the back of the service manual. PS> I have built generator/alternators . All generate electricity and the byproduct is ALWAYS heat.heat. This just happens to be one design with less than stellar parts and ability to draw the heat out.If you can't get 7-10k out of a stator...you surely have something very wrong But still, I am on my original stator close to 33kmiles. Maybe I'm the luckiest SOB out here?

I thought it was a basic assumption that we're not talking about sitting there at idle, that's obviously not max power. I dont know how you get ten thousand miles out of a stator staying below 3k rpm, but everyone else i know rides above that, meaning the stator is under 100% load 100% of the time. Rereading what you wrote i think about 5 times, i dont think you're actually refuting what im saying, sooooo... Yes, the stator is under 100 percent demand 100 percent of the time. The heat comes out in the regulator, not in the stator.

[Brian Moffet]

Actually, Jason is correct. And you are to a point as well.  For a given RPM, the stator is producing a consistent voltage.  Say at 5000 RPM, the stator generates 20 volts RMS.  The regulator/rectifier will clamp that down to 14 volts (or around there).  So you are correct, the voltage is always at max coming out of the regulator/rectifier.  That is what the shunt is for in the regulator/rectifier.  And that does produce a lot of heat in the R/R.

However, that is not all that is going on.  The voltage is controlled by the RPM on the stator.  The current draw is controlled by the resistance in the bike after the R/R.  As you add more load, that resistance is going to drop, because all of those loads are in parallel, you can calculate the load as 1/R1 + 1/R2 + 1/R3 ... = 1/Rtotal.  You have 14 volts, V = IR gives you I = V/R.  As R drops because of more loads your current I has to increase given that your voltage is constant.

This is exactly the same thing as a generator powering a house-hold current.  It chugs along happily while the load is low, but as the load increases it uses more power to maintain the voltage.  

Since the current is now increasing, the heat produced in the wires in the stator (remember they are at constant voltage for a given RPM) also increases. Power output of a resistance is P = VI.   Voltage stays constant, so as the current goes up the power has to go up. That power is heat.

What clicked this for me was someone reminding me that the voltage is directly related to the RPM in a generation circuit. (yes, it's been a long time since I thought about this in physics, over 2 decades now.  In that time I got comfortable with slightly incorrect ideas.)  Given that reminder, the rest fell into place given the basic formulas  Voltage = Current * Resistance and Power = Voltage * Current.  That and I was riding an exercise bicycle that has an adjustment which basically is the same as increasing load on the bike.  When I increased the load, I had to work a lot harder to maintain the RPM.

I don't know if this changes anyones mind or not, but it's my belief.

Brian

[fret not]

Has anyone here tried a stator from RMSTAOR?  At the very least they have a great application chart that shows many other bikes that use the same stator, so it opens up a pretty big field to re cycle from.  They also have regulator/rectifier in a couple versions.  One listed as "heavy duty".  Anyone?

[Tiger]

 :) Here ya go fret...(I posted this some time ago... ;) )

:) Here is a list of other bikes that use the G7 stator (same as the Vision... 8) )

YAMAHA...

1987-96 XV535 Virago
1988-95 XV750 Virago
1992-93 TDM850
1986-88 XV1000 Virago
1987-97 XV1100 Virago

HONDA...

1983-86 VT500c Shadow
1983-84 VT500FT Ascot
1988-01 VLX600-VT600 Shadow
1987-96 XL600V Transalp
1996-99 CBR900RR
2000-03 CBR929RR

SUZUKI...

1985-87 VS700 Intruder
1992-99 VS800 Intruder
1990-92 VX800
1998-01 VL1500 Intruder

APRILLIA...

1999-02 SL1000 Falco
1999-02 RSV Mille
2001-02 RST Futura
2002.... ETV Caponord

BMW...
1997-01 F650

Cut and paste or print off ;)

There are others...feel free to add on to this thread 8)

                    8).......TIGER....... 8)

[vadasz1]

I did a quick ebay search for "XV1100 + stator" and came up with these babies.  Cheaper too.
http://shop.ebay.com/?_from=R40&_trksid=p3907.m38.l1313&_nkw=XV1100+%2B+stator&_sacat=See-All-Categories

And cheaper still....
http://shop.ebay.com/i.html?_nkw=VS700+%2B+stator&_sacat=0&_trksid=p3286.m270.l1313&_odkw=VL1500+%2B+stator&_osacat=0

HONDA cheaper still......
http://shop.ebay.com/i.html?_nkw=VT500FT+%2B+stator&_sacat=0&_trksid=p3286.m270.l1313&_odkw=VT600+%2B+stator&_osacat=0
http://shop.ebay.com/i.html?_nkw=VT500c+%2B+stator&_sacat=0&_trksid=p3286.m270.l1313&_dmpt=Motorcycles_Parts_Accessories&_odkw=VT500FT+%2B+stator&_osacat=0

[kev10104]

$28 for the Honda one.What a difference!

[Night Vision]

I'm currently running a shadow stator in one of my Visions....

what one needs to keep in mind is that the "list" is based on inner and outer diameters measurements of the G7 type stator...

although lots of them are the same "size", their wiring / windings may be slightly different.... the exit points of the wiring on the shadow stator I used  just barely lined up where the wires need to be (held in place with that holder thingy)

[George R. Young]

While replacing Vision stators I had a lot of time to think about this:

The stator open-circuit voltage increases with RPM, say some constant V * RPM.

The stator winding acts like an inductor, and its impedance increases with RPM (frequency), say some constant Z * RPM.

Here's the approximation part:
At most RPMs, the open circuit stator voltage is much greater than 12, so the load seen by the alternator appears to be a short circuit. Another way of saying this is that the output current is limited only by the alternator internal impedance. This approximation is not very good at idle, but at any riding RPM, e.g. 3500 or more, it's pretty good.

Given that approximation, the output current is constant, i.e. (V*RPM)/Z*RPM).

Some of the output current runs the lights and the ignition, the rest heats the regulator. The exact same total current flows through the wires of the stator and heats them up too.

Same current, same heating effect all the time. Unlike an excited-field alternator.

These hot wires are 'cooled' by oil splash, and the oil is pretty hot to start with.

That's why the insulation gets black and eventually breaks down, allowing the stator to short to ground. Because it's producing full output all the time and current in the wire generates heat.

This design is cheap, and it usually lasts longer than the warranty. Makes me sick.

[Brian Moffet]

Here's the approximation part:
At most RPMs, the open circuit stator voltage is much greater than 12, so the load seen by the alternator appears to be a short circuit. Another way of saying this is that the output current is limited only by the alternator internal impedance. This approximation is not very good at idle, but at any riding RPM, e.g. 3500 or more, it's pretty good.

I think there is a flaw in this approximation.  Assume that the voltage is rectified to always be positive.  

Anything above 14 volts is shorted to ground via a resistor, or something equivalent.  What that means is that for everything below 14 volts, the outside resistance is the bike electrics, for above 14 volts it is the regulator.  So you basically have a system that has two resistors, one that is active below 14 volts (the bike load) and one that is active above 14 volts (the regulator).

What this also means, practically, is that the more load you put on the system the more power it takes from the engine to drive that load (because the current is increases with the load).

Unfortunately, the way to prove this would be to see whether there is a decrease in power available when you turn on more load.  If you hooked up your motorcycle regulator to a generator/stator on a bicycle so that you are providing the power (there are lots of people who have done this) then you can actually tell when you add more load because you have to pedal harder to keep the current requirements going.

Brian

[jasonm.]

There is significant heat out of the stator. Why do you think they turn black. Why did Yamaha put a cooling mod. in the Ventures.aka 2 Vision engines ?  Heat is always a result of an AC generator. Flux lines do cause heat. And the faster the engine spins. The more heat thru the windings. But maybe you missed that class? And the regulator gets hot from it's job of doing R/R and it's not rest and relaxation.  Put your hand on the left engine case after starting cold. It gets warmer much faster than the right side. My heat gun does not lie...nor my hand.  Heat is always the culprit. Just which dies 1st...the R/R or the stator?  Inanecathode; I think we are saying the same thing. Just 2 different ways. This Spring I will be installing a MOSFET R/R on both my bikes. These are now on many bikes. Including the latest Vmax. These are suppose to be more efficient at doing the required job. And supposedly less "voltage spikes"...if that's important?

[fret not]

Jasonm, is that MOSFET r/r a modification to the original r/r or another project we have to make ourselves, or an aftermarket item?

[inanecathode]

Uhg. I stopped counting at six the times this discussion has happened.

Look. Here's how you fix it. Wind a better stator, there. Extremely high temp insulation, cast stator core, epoxy coated stator poles. Doesnt matter how crappy your charging system is, if you can't break it it wont break.

If part of my bike keeps falling off, i'm not going to find a different way of riding so it stays attached, i'm going to bolt that stupid thing down better.

[kev10104]

Makes sense.lol

[jasonm.]

Jasonm, is that MOSFET r/r a modification to the original r/r or another project we have to make ourselves, or an aftermarket item?

THERE WAS A "GROUP PURCHASE"  on the Venture site I go to. For these MOSFET R/R's. Venturerider.org  I bought 2 of these. I will do this MOD. in the Spring.  FYI, were very inexpensive. I could not resist.

[fret not]

Thanks Jason, keep us posted.