Impulse Nytro blowing belts

quadtrac

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Feb 27, 2009
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Have a 2012 Nytro with the impulse turbo kit on it. Track is a 165x16x3 and I'm running it about 17lbs of boost at elevation. If I ride the sled fairly hard I can blow 1 belt a day. So far just using the factory yamaha belts, don't know if anybody makes something better for this application? Is it common to blow belts when you get up around 300hp? I would almost assume it is when that belt was only designed for a stock 130hp Nytro lol
 

motojunkie101

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I would check your clutch alignment, that doesn't seem normal to me on a Yamaha. I'd look at your motor mounts as well, the horsepower could be torquing the engine enough to throw the clutches out of alignment too. Check runout at the primary and secondary, and the shaft bearings too. I've heard of sleds bending the crank when the belt lets go at full tilt.

I thought the impulse kit was 270hp? I think the MCX at 15lbs was 240...either way at 17lbs you shouldn't be blowing a belt a day, even running the 8DN.
 

n2otoofast4u

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Oct 3, 2010
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Welcome to the world of boosted Nytros. I aligned clutches, changed mounts, machined the clutches, blah, blah, blah. I could never get the thing to hold a belt more than 60-80 miles.
 

quadtrac

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I also have a push turbo Nytro that should be roughly around 200hp... That sled is still on the same belt after 4 years now! Guessing I'm probably not giving the belt enough time to cool down between big pulls. Going to add some more vents in the panels and see if that helps any.
 

BradM8

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Aug 5, 2012
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Is it just the way the picture looks or is it outside circumference of the primary all chunked up?
 

motojunkie101

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I also have a push turbo Nytro that should be roughly around 200hp... That sled is still on the same belt after 4 years now! Guessing I'm probably not giving the belt enough time to cool down between big pulls. Going to add some more vents in the panels and see if that helps any.
That was going to be my next suggestion, see if you can add some cooling with a vent kit, and seal up any holes that could be letting in snow.

I'd also look at your clutching, your belt could be slipping and creating extra heat.
 

motojunkie101

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This threat pointed out what could be an obvious cause:
https://www.snowest.com/forum/showthread.php?t=370841


Your clutches also look like they could use a good cleaning, Pull them off and blow them out with an air compressor, then follow up with brake cleaner. Any belt debris can cause binding and extra heat.

Once they are clean, check all the bushings, rollers, ramps ect for anything that is worn out and replace as needed. I'm guessing you have a few thousand miles on your sled so the clutches probably need some attention along with bearings and the chain/chaincase while you have it in the garage.
 

sledfvr

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Apr 7, 2008
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I run apex's and didn't blow belts with the 162. Once I went to 174x3 I started having belt issues. That being said if I shut them off and let things cool a bit then they hold up ok.

For Apex's I run

blue/white/blue primary spring with dtya-3 dalton weights, you may want dtya-2

secondary is red/white cutler spring, 8bv71 helix wrapped to 2-3

Should be similar for a nytro. Looks like you may have the stock seconday spring and this won't clamp the belt hard enough to prevent slipping.
 

richyrich

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Also by the look of the panel with the Impulse screen, it appears to be warped inward quite a bit. What turbo setup are you running. Meaning, are you running the 2860, or the 2871 with separated waste-gate, and do you have in fact everything freshly wrapped with header wrap to contain the heat as much as possible. The bigger turbo with a bigger exhaust pipe will put out more heat, which is very close to the clutches. I'm not saying it's the sole factor, but it could be a big contributor.