ok, so the bottom line for all of this is that we need to get our shift out points to where our pk hp and tq is.. I have yet to see any real dyno numbers on a stock or modded V. BUt, I would assume that peak HP occurs a few hundred rpm after peak tq? Is that correct?

 

Yep, I would go only with a complete kit that keeps your motor near peak power. Dalton or EPI.

I tried to post all of my runs months ago. This site still says..."Pending Approval". So I gave up.

You right , were the torque and HP "usually" occurs. If I remember right, my runs show peak torque
at around 5000rpm. Ideally, in a perfect world, you would want to maintain peak torque in the first
2 gears, then , let the HP carry you to the top end(Trap speed) with the remaining ratios. Ive asked
a friend of mine if this really applies. Quote, "why the hell do you think I shift 500rpm sooner in 1st and
2nd.... Duh...?"

Get this, his friend challenged me to a 100ft motorcycle drag race. Yeah, I'll kick your A#$. I didn't
know it at first, but I was challanging Chipp Ellis-Team Green. You would be surprised who you run
into and have no clue when to keep your mouth shut. I never heard the end of it.

Memories.....

 

Here's an old post from the Polaris forum. Make no mistake, the Polaris guys with the snowmobiles and the radical Sport 400's know their CVT's better than anyone else. Like I said, there's has to be a reason ALL the Polaris performance companies use crank HP instead of RWHP.


"Keep in mind that one of the functions of the cvt is to keep the motor in it's power band. Polaris has no rev limiter. The cvt operates on torque feedback from the rear wheels. As the
load from the dyno changes; the cvt will sense it and continuously shift. A standard trannied quad such as a Banshee will be placed in fourth gear and revved out on a dyno for consistant
readings. The tranny is locked in and no shifting occurs.
If I have this correctly; a dyno measures how fast the inertia roller is accellerated within a given time. Depending how much engagement that you have dialed into the cvt; you can change this accelleration figure and fool the dyno. For example; I install a light primary spring and heavy weights. The bike will accellerate slowly due to the heavier weights and lower engagement speed. This will give poor dyno readings due to the lackluster accelleration. Now; take the same motor and install a heavy spring with the same weights. The bike revs to a higher r.p.m. before engagement and engages violently. This in turn accellerates the dyno drum much quicker than the previous setup with the same motor. What's the dyno going to read? More h.p.
If you talk to some of the biggest names in sled clutching, such as Bartell or Redline; they'll laugh at the mention of a track dyno. If you go to a sled drag event; you'll see how these cvt's are really tuned. They use timing lights, onboard computers and tachs. AEEN has developed a $150,000.00 water brake dyno to measure the h.p. It is believed to be one of the most accurate dynos built. Guess what he uses for clutching? Timed runs on the track. Sled manufacturers dyno at the crank as well. CPI; well known for their sled pipes; dyno at the crank. HPD; who built mine and AZ400L's engines; has the world land speed record in a 600' run on a sled. 190 m.p.h.!!! This record is old and has never been beaten. Was the dyno used for clutching? Nope. Too many variables in the cvt.
AEEN, PSI,Hot Seat, HPD, CPI all show the Polaris 400 atv engine making peak h.p. in the area of 6300 r.p.m. up to 7500 r.p.m. Are all these aftermarket vendors wrong compared to Ohton's dyno readings? I don't think so; or they'd all be out of business. Charlies dyno shows Jerry's bike making peak h.p. at 4800 r.p.m. Anybody who's worked with large bore two strokes knows that this is grossly incorrect. The tach on the dyno showed Jerry making peak h.p. at 8000 r.p.m. repeatedly. The dyno printout showed peak h.p. at 4800 r.p.m. Figure that one out. If I clutched Jerry's bike for 4800 r.p.m., following the dyno chart; it would be a complete dog in the sand. Hell; I and others set our engagement r.p.m.'s well over 3500.
I'm not trying to make this out to be a big controversy. Basically; i'm trying to give a better explanation of the dynos effects on the cvt. Until we can determine what's going on between the cvt and dyno; we can't rely on it's readings for tuning. Hopefully; Charlie will soon grasp the cvt and determine what changes could be made in the dyno process. He's a great guy and very smart. I have a feeling he'll come up with something. Hope this helps and look forward to your response."

 

KevinM,

You are exactly right, any dyno run on a cvt machine is severely skewed as to the actual power that a motor is producing. I have tried to explain that the CVT settings affect the dyno readings and have run into a brick wall every time--people just don't understand the concept.

 

Wanting to "tune" your clutch and only wanting to change springs is a joke.

Does it help. sure if you have the right spring for the condition of your bike. Arguing back and forth doesn't really help anyone. Everyone's bike on here is different, jetting, gas, elevation, tires, bearings, belt conditions, how clear your clutches are, different racing conditions, weight of the driver, it's hard to say "this is the best spring".

Samcoed, who had the V that beat most of the big bore bikes, rappys, Boms and others at the APPT races in Texas this year, emailed me for help with his clutching. We were two weeks of emailing back and forth before ending with the best combo. Do this, do that, if it does this then do that. That was before there was all these choices. We had to lighten the clutches, use a combo of weights and springs that were available at the time. Don't get me wrong, clutching wasn't the only thing done to the bike to make it fast, but he reported several MPH faster and quicker times with the changes made.

clutching 101. get a tach, mark off 300 feet, run timed trails or have a friend or someone to race against, someone as a constant, so you can tell if your gaining or loosing. Make changes, and try different things, don't buy anything that can't be sent back. Test..Test..test.

I use a digitron playback tach, it records rpm's and times for playback after the run. I run adjustable weights, if my RPM's are down I move the weight around on the weight itself. I have lightened my clutches to make up for bigger, wider tires, more trackion without losing HP. I run a more aggrisive curve on my weights, look at the curve on a snowmoble weight compared to the barely curves weights of the V.
There's lot of different things that can be done, from just a spring.

I think that any kit you would buy would be an improvement over stock. I'm sure EPI have knowledgeable people.

I know that Dalton knows what their doing from the years of racing sleds against us. I talked about lightening the clutch plate on the forum and three weeks later Dale had an lightened overdrive clutch plate maded. He's racing his V and has the video to show, I sure he know his stuff.

Talk to both and see what you think. oh ya, ask about their return policy.

 

I understand. What we need is an engine only dyno. I have a hell of a time dynoing my car. Darn stall is an unlocked type and I can't ever get good readings.

 

Where are you guys seeing an inaccuracy???

The CVT, when given full throttle, goes directly to the shiftout point and STAYS THERE until the trans gets to it's final drive ratio.

The only reading you should be analyizing is your shiftout rpm/hp/torque and above.
Anything below that would be nothing to look at.

 

I would think max HP occuring on a 2-stroke 400 at 4800 was alittle off too. No question. And having the availability of a crank type dyno would be a significant advantage. Now you would know, without any doubt, were max HP occurs. Most people don't have that option or even the availability of an inertia dyno. So they rely on recommendations of others.

Now accelerating a specific mass drum within a specified time frame can be used to determine Torque and HP thru mathematics. Changing the weights and springs will significantly effect the readings...absolutely. Think about it, If in fact, you are accelerating the 500lb drum quicker and faster, Aren't you really planting more HP to the rear wheels? Yep. This concept is valid if you use common sense with the primary spring and keep engagement about the same. Your starting MPH has an effect as well. As soon as a V hits 50mph or so, you are shifted totally out to 1:1. Now, what's in question is the actual HP number. I AGREE. It BS on a CVT! Screw the number. The goal is to achieve the highest number possible and maintain it there regardless of its value. This is your starting point. Then you go to the real world with timing lights and radar guns to see if you are close and adjust from there.

This is what people told me from Hot to Go (Sleds) and EPI. I have no idea how sleds and there track/trans effect the CVT...maybe even more so than an ATV

 

Amen! That's what it's all about.

And that brings it back to the original point about lowering the shiftout point.
The stock V unmodded motor, air box, anything..... ALL STOCK, seems to run out of steam up top. So why not lower your shiftout point and gain the torque of the V?
EPI seems to totally agree and they explained it thoroughly also.

 

That's the exact point I'm trying to make. Make your changes and then take it to the dirt. Theory looks nice on these forums, but results out on the trails are what matters.