Note that the guy had his coil pickup wrong so you need to double the rpms. A ninja 250 just before me did 27 HP but I didn't get the torque on it. The dyno operator said his 82 kz750 Twin (not four) did a about the same HP but 15 lbs LESS torque, interesting! This was at an open house where if you purchased $25.00 or more you run on this small portable dyno. I purchased one of those little volt meters with time and temperature.
Since the document was pdf (adobe reader) I posted a link to my public folder on sky drive. Click the link and it will take you to the file to downolad and view.
http://cid-fbf69431aae6cb93.skydrive.live.com/self.aspx/.Public/File0001.pdf
David via Don
I'm surprised the torque was that much since the claimed is only 37 @8500rpm
guess you got a little torque monster there Don :)
oh god, look at the lumps on the torque curve! the stock vision carbs, SOOO BAD!
The kZ750 twin has a reputation of being a turd, so I;m not surprised.
4 valve engines like the vision, usually produce good torque .
Oh I see....now. Only 43hp. ???
Hum, I also had about that on my '82. But my '83 had almost 55hp at it's lest test. I should test my '83 again since I have messed with it quite a bit . I believe I increased my torque but lowered my peak hp. to maybe 50.
Take this dyno with a grain of salt, it was portable unit and they only did one run (well what do you expect for free). I can see from the torque figure why you hardly ever have to shift these bikes out on the road. As for the KZ750, I asked the operator for somethinkg to compare to and since he apparently has one he know the figures for that, wish I had asked him for some other figures. yes, the torque figure is confusing as specifications do only give 37 ft lbs, I wonder if there is some difference in the math or standards, I'm not surprized on the HP as this was a rear wheel, on the bike pull, I would think the published 65 HP figure is just off the crank. In watching my bike on the dyno I can see I need to balance my rear tire and I'll bet I'm running a bit rich.
I'm kind of glad they didn't try to do another run or two as I think even that one run took a few hundred miles off my rear tire!
Thank you yellow jacket for helping to post this!
Quote from: Rick G on May 17, 2009, 03:47:49 PM
The kZ750 twin has a reputation of being a turd, so I;m not surprised.
4 valve engines like the vision, usually produce good torque .
??? I thought torque was a factor of the bore and stroke and a better valve train affects top end breathe ability / HP ???
Quote from: Kid Jedi on May 17, 2009, 11:08:18 PM
Quote from: Rick G on May 17, 2009, 03:47:49 PM
The kZ750 twin has a reputation of being a turd, so I;m not surprised.
4 valve engines like the vision, usually produce good torque .
??? I thought torque was a factor of the bore and stroke and a better valve train affects top end breathe ability / HP ???
Yes and no. Better, faster, and more efficient valve closing equates to higher and quicker combustion pressure. More pressure = more torque. Hence partially why diesels can pull stumps.
think the v could run 12.0 to 1 with out cam modification? I think she can....
Do you have a secret source of HiComp pistons?
Yup. The pistion company owes me a favor (Sold em 2 square feet of tantalum for 500 bucks, loooong story) , They said they would be willing to make pistons for my V, normally they only make em in sets of at least 8 and i don't wanna try to buy in with 3 other visionarys...
Besides, the pistons & rods in the v are VERY OLD tech compared to what is available now. a lot of advancement in steel/ aluminum manufacturing has come out in the last 10 years.
Don, Do you still have the restrictors in your carburetors?
I be happy with a set of 1st or 2nd over pistons and rings, in the stock compression ratio.
Using a long stroke small bore engine is an old idea to get torque , Big bore short stroke ,with lots of valve area in a 4 valve configuration is far superior.
If you have custom sources, go for big bore 650cc items. From what I've read here, from someone that built a hot rod V (name unknown to me now) V cylinders will bore to 650. Imagine that with 12 to 1. Better run Premium grade.
FYI- the rods and associated bearings in the "V" won't last at 12:1 and 650cc. Just go to 650cc.
Ron, yes I still have the restrictors on my carbs. Maybe in couple of weeks I'll give the bike a good going over and take em off and see how it runs. As far as I know I still have the caps over the mixture screws on my carbs, plus I'll bet the mixture screws are frozen up by now anyway.
You know it gets to a point where the bike starts fine and runs great, do I really want to mess with it? On the other hand my MPG seems down and perhaps some adjustment and redoing some things is probably a good idea-I've been thinking I must be running rich for the last year or so. I haven't really messed with the V for awhile other then putting the monometer on perhaps about two times each summer (and of course changing oil, plugs).
Tell me your thoughts!
if it aint broken...
and i think a 50cc/ pistion overbore on the engine would be excessive. after a niskil coating I wouldn't have to worry about new pistions/rings EVER again, provided i change my oil, but i don't think the bottom end can take much more. 58ft lbs o' torque is ALOT for that little tranny. if i went to 12-1 pisitons i could install MUCH lighter ones, possibly 1/2 as heavy, meaning that the rods and bearings would be doing less work. to offset the extra work of 12-1
Quote from: Ron_McCoy on May 17, 2009, 11:30:05 PM
Don, Do you still have the restrictors in your carburetors?
good point! the way they restrict the hp in Europe for beginner riders is a restrictor plate kit...
Quote from: don_vanecek on May 18, 2009, 09:49:03 AM
Tell me your thoughts!
life is too short... crack open them carbs this winter!
my brother doesn't have a vac flapper so don't let that worry you.
2 nickels on the flapper and he gets over 50mpg consistantly and it's not on flatlands either.
I'll get some new plugs next chance I get and do some experimentation. By the way my flappper door is long gone, I can see where the rivets are, but I don't remember even having one (and I'm the original owner).
Well we will see what happens!
Don -
Air box tops are pretty common. I have an original non-vacuum type. If you want it, a donation to the ROV site will get it to you.
H2O
Thanks Robert, I'll keep that in mind but first I want to see what happens with either no plates or a reduction in their size. Sure would like to see you in Valentine in July but it's just abit too far a drive. I found the star clubs web site, looks like quite an event!
restricters? wha
GT, I am the original owner of my Vision purchased in 1984. By perhaps the second or third year I owned it, first I had the problem with the inside of the gas tank rusting away then, a bad case of Vision lag. I never knew about Yamaha's fix for this (and a curse on my dealer-who of course is years out of business-his former shop is a video rental store now-he should have known about the fix!)
When farmers still drove their horses to town and we corresponded by snail mail, ROV existed as a quarterly small newspaper(sort of). One of the members back then-who although he apparently knew about the factory fix, wanted to install separate pod filters on his Vision. He wrote a several page article on this and he actually did some very extensive jetting to his carbs including even having his dentist do some drilling on them. But to make up for having no flapper door etc, he noted that one of the problems with the Vision carbs was, quote "The main problem with the carbs is the top opening is alot larger then the inside barrel that goes to the intakes. The power nozzle works from vaccum, so when the top opening is made smaller, closer to the size of the inside of the carb, this gives you better vaccum all the way to the top of the carb,"
So, he cut from tin, small semi circle plates that the longest side is 2 7/32 inches long and these fit over the top of the carbs. I of course cleaned my carbs, kreemed my tank (no POR back then), installed a fuel filter, installed #130 main jets in each carb and made the little tin plates as this man described. All I know is that after that no more Vision lag, and a power band, well, as you can see on the dyno results, a mile wide.
I am alittle puzzled this last year or so however that in spite of how well the bike runs my mpg seems to not be what is used to be, I'll pull my tank off shortly and first do what I haven't done before and see what the bike runs like without them at all, if lag returns then I think I will try different sizing-but I don't want to size them to apoint they could get sucked into the engine.
If you want any further info on this PM me and I can send you a copy (by snail mail) of the guys article (13 pages-some of it won't copy real great). His name was Andrew Biehle of Vernon, IN, have no idea whatever happened to him or his Vision.
So, I'm in the grocery store today reading a motorcycle mag of some sort and one of there tests is of an 883 Harley. The dyno on the Harley gave like 46 hp and 49 lbs touque, from 883 cc's! I wonder how close the dyno run I did compares??? If these are comparable readings won't do you any good to buy one of those! Of course there were also sport bike tests with dyno figures of 100 plus HP!
that torque graph reading is WAY off the mark. The scale the guy used must be off by about 20ft/lbs. 58 ft/lb is normal for 1000cc bikes not 550s. I have the original Yamaha specs from Yamaha themselves. They rate these at about 37ft/lb peak. You don't have 58ft/lb. Otherwise you'd be doing power wheelies everywhere. Or smoking the tires at will.
Don, the 883 Sportster is a long stroke , 2 valve , push rod engine, that was developed in 1954. , plus the bike is pretty heavy.
A Vision should have no problem dispatching a 883.
O.K. Don.
I'll vouch for you on the gas milage being worse....
Cheers Ken S.
I have taken my plates off, guess what, almost no difference! Seat of the pants seems to tell me I have to watch my throttle hand just alttle more at low rpms-but no Vision lag, it seems like the 7-9 thousand area is a little stronger, haven't burned enough tanks yet to see if mpg is better yet.
Now I do have 130 main jets in each carb plus my own manometer which I put on and set the carbs as equal as possible and I apparently must have been successful in my last carb cleaning, gosh, over three years ago already, my how time flys!
Oh, and I would not be surprised that this dyno run is possibly only good for comparing one bike to other bikes ran on the same dyno-I wish I had BS'ed with the operator more and of course it didn't really surprise me when he told me the figures from his KZ750 (twin) as I have no doubt a V will out run one. Those KZ750 twins were from a time when the MC manufactures just built all sorts of bikes, some you weren't sure why they bothered, but you sure had a lot of stuff to pick from in the late 70's, early eighty's!
what?! restrictors in the carbs???
What piece of the carb are we talking about, I want to get rid of it.
Ironic looking at the HP and torque curves that the peak is right where a lot of these bikes run poorly :(
Don had some custom restrictor plates installed on the tops of the carbs. It was another attempt to fix the Vision Stumble and the original non-vacuum airbox. I'd read about that fix years ago, but had never seen any or heard any reports on their functionality until Don came to the 25 year party a couple years ago.
Those restrictors weren't very common and not likely found on anyone's Vision (besides Don's) these days.
H2O
ah...
Has anybody ever tried the tornado idea?
For a fuel injected car, it helps atomize the air to swirl, but on a carbureted vehicle, straight airpath is better for the venturi's. Maybe I'll cut up a pop can and make some air straightening fins to mount under the air filter in the hoses above the carbs :)
if using the stock front required the larger pilots.For what it's worth. 130 mains on the '82's is too rich. The stock #60 pilots require the smaller mains than the '83 model. The front head pipes are larger i.d. than the '83. If using MACs...then the above may not mean much. ALso on the '82 I had. All stumbles were due to it being too rich. Those #60 pilots are the largest used on ANY Jap bike back then. My low speed screws were set for perfect idle w/digi-tach & I kept my flapper slightly open more than stock at idle. Stumble gone. AND that tornado thing is a load of crap! It is simply a restictor. Your fuel injectors in the car are what determine atomization. The tornado restricts flow thus lowering the air flow=better mpg but also less power. You will never see them prove "more power" just better mpg.
Quote from: Jimustanguitar on June 09, 2009, 06:37:24 PM
ah...
Has anybody ever tried the tornado idea?
For a fuel injected car, it helps atomize the air to swirl, but on a carbureted vehicle, straight airpath is better for the venturi's. Maybe I'll cut up a pop can and make some air straightening fins to mount under the air filter in the hoses above the carbs :)
I've never seen any reliable data to support them. Just infomercials.
David
Just to continue the Dyno theme of this thread this is the one I am planning to be on next week http://www.absmotorcycles.co.nz/tune.html I work there and am part of the ahem..... "Dyno team" (which as you can see from the size of the room is not very big ;D ;D ), no matter seeing/hearing some of the exhaust development work on the latest Duc's and the corresponding HP gains firsthand gives hope for the XZ. As an overall result there is an average of 12% gain with the hand built stainless systems coming out of the shop and that is without any other mods and this is an XZ550 friendly shop from way back ;D ;D ;D
I'm still looking for a source of larger hi rev friendly pistons if anyone has any ideas.
This run will be for a bottom line test to act as a base for future developments. I am using my current day to day setup, flapper box, no YICS, jet sizes unknown (I'm not going to explore while it's going so well), and CycleWorks pipes, running on 95 with a touch of acetone.
I have just checked the shims as a precaution as she has a tendency to rev way past 11,000 in the twisties if one is not paying attention ::) without seemingly any loss of performance. Mind you in the thrill of the chase who actually knows so I might just explore the upper range while on the Dyno if it feels right on the day. I was pleasantly surprised with the shim check as it was a touch overdue at 17,300 and a lot of hard use but all were within spec.
Hi rev pistons are not really the best way to go on this model, since the skirt length has to be long to make up for the V twin engine, the crank angles saw to that, the way to go is hi comp.
Dont worry about over rev till you get to about 85k on the motor. the redline was designated with late engine tolerances in mind so your redline is actually closer to 12K , and will creep down as the rods stretch and the main bearings wear out.
JUST CHANGE YOUR OIL! If you are gonna flog your bike like a race machine run some oil designed for an in which the engine and transmission are in the same case!
It will be interesting to see what you find out. Remember, my test was on this portable machine set up in a parking lot and was just a freebie if you make a purchase (heck, they didn't even ask me to prove my purchase). Sure wish I had BS'ed with guy more-wonder if this store (sort of their spring open house) will do this again next year!