2008 mtx 153 DESTROYING BELTS

[bslade93]

Gotta quick question for all the clutch guru's out there I own a 2008 nytro mtx 153 and it is constantly hitting the rev limiter and exploding belts my guess is where the nytro is clutched for about 8000 feet from the factory that there's not enough weight in the clutch for where I ride (500-1500 feet) only thing I have done to the motor is a mbrp exhaust. any suggestions on how to fix this would be greatly appreciated.

 

[APEX 06]

rebuild the primary clutch, clean them and and venting for cooling

 

[bslade93]

rebuild the primary clutch, clean them and and venting for cooling

There's only 5000 kilometers on the sled, also I doubt cooling should be a problem as for I run all woods in deep snow and its mostly 30 to 60 below all year round. however ill try this! thanks for the info!

 

[Stoli]

quick math is about 3000 miles roughly. I have aprox 1200 miles and was blowing belts badly - one day 3 in a day.
while your clutches could be mis-aligned and dirty - that is most likely not the issue - Ulmer sells a nifty tool to check - I used it and mine were slightly off. I would agree that the rev limiter under full load is blowing belts. Are they separating or breaking?
The helix on a stock MTX has a different degree to it them most kits run at lower elevation and the weights also have a different engaging angle.

I would give one of the sponsors a ring - ulmer or ricky at OFT. They have clutch kits that will fix your issue.

As a note - i will be running daltons this year. After much trial and error with a buddy's sled and mine - his was much better so i will be running what he had and I'm running the stock helix both low and high elevation now.

What spring do you have?

 

[pro116]

If you are hitting the rev limiter you need to clutch heavier and if you are doing long blast with the stock gearing you are running out of gear which is what is causing your belts to blow.

 

[bslade93]

If you are hitting the rev limiter you need to clutch heavier and if you are doing long blast with the stock gearing you are running out of gear which is what is causing your belts to blow.

Definitely going to go with an ulmer clutch kit and maybe get a 22 tooth top gear?

 

[rlcofmn]

22 tooth upper is the Yamaha spec for low altitude 08 153. However we go to a 20 on all our stuff in AK (low elevation) to me it just sounds like you're light on your primary weights or if your riding in low snow conditions you may benefit from more helix like the RTX/XTX 43 degree. On our non turbo stuff we use all stock parts and it works well. 22/40 gearing is too much for a mountain sled unless you're running big power on a turbo sled.

 

[Off Trail Mike]

I've run the stock low altitiude 22/40 gearing (1500-2500 feet) on my MTX. Works well, no belt issues whatsoever in 3000km's but if you are going to be in powder alot, I'd follow rlcofmn's suggestion and gear down to 21. It extends your belt life even more, better throttle modulation down low and there is virtually no top end difference.

I'd check your clutches for smooth action(bushings/Arms/rollers/etc), as it takes 10 minutes to remove the six bolts in the primary and 3 in the secondary, but like the other guys said, if you are bouncing off the rev limiter @ 9400rpm, your belt is going to overheat and blow. CVT belts don't work well at anything above 9000 rpm (even that is too high).

There is a reason why they gear down the apex engine from 10,500rpm!

OTM