Don Vancek's Dyno Test Report

[don_vanecek]

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!

[GT @ oh.]

restricters? wha

[don_vanecek]

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.   
   

[don_vanecek]

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!

[jasonm.]

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.

[Rick G]

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.

[Kenny]

  O.K.  Don.
   I'll vouch for you on the gas milage being worse....
                  Cheers Ken S.   

[don_vanecek]

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! 

[Jimustanguitar]

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 :(

[h2olawyer]

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

[Jimustanguitar]

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  :)

[jasonm.]

 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.

[YellowJacket!]

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

[treedragon]

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.

[Kid Jedi]

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!

[don_vanecek]

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!