I just got a new sled this year (AC M8) and have been learning about clutching. I changed out the helix, changed the primary spring, added adjustable weights with huge improvements.

I didn't do squat to my Grizz, didn't know too. There are massive improvements to be made with proper tuning. Wonder why ATV's are so far behind snowmobiles?


I was thinking on looking up some dyno charts and seeing what my 05 Grizz is even suppose to tach, then tune to that RPM. Perhaps I'll even find a dual or tripple stage helix. Does Yamaha even sell multiple helix angles?

after that maybe I'll hook up some boss noss [img]i/expressions/face-icon-small-happy.gif[/img]

 

if your sled is a 2 stroke theres alot of differnces in how power is transfered vs. a 4 stroke. some clutch tuning on some models do help in the power game w/ a pipe and proper jetting.

 

It does help http://i126.photobucket.com/albums/p...ucepic2089.jpg

 

Nice picture.
Yamaha ultramatic trannys arent your typical cvt snowmobile setup( unlike the polaris cvt, which is very much snowmobile in heritage, and has alot of after market for clutch changing).Theres a centrifical clutch before the primary, and that to a large degree, controls when the primary starts turning. The springs on the centrifical clutch can be changed to stronger springs, which resist engaging til a higher rpm. The secondary helix , as far as i know, isnt changable like on a Polaris...in fact i dont know of any other (than stock) which is made. The secondary spring can be changed, to keep up with the mods on the primary, like clutch weight changes, but thats about all that can be changed on the secondary.
The weights on the primary are changable, but unless youre a machinist, youre limited to what is sold, and some guys use the weights from a 450 kodiak, which are lighter, and that raises the rpm per mph.
Because the motor is a 660 4 stroke, it has plenty of torque at lower rpm, and thats how the clutch is tuned. You can change what you will...but bottom line, not much is gonna change with the performance, unlike a snowmobile.

 

Good Post....

 

while I sort of disagree that clutch tuning won't make that much of a difference on an ATV, basically I agree with Hondabuster - utility ATVs are hardly high performance and the gains for general use probably don't outweigh the cost or time. However, I'll bet you most of the guys that win pulls have clutched their machine.

 

I would have to disagree with the people who say that you can't gain much by tuneing you clutch .