Breaking drive belts

[kchart18]

Hey Guys. I have a schwinn campus 50 with a few upgrades. Did a 70cc piston, cylinder, and a performance head. also drilled some of the baffles in the exhaust, replaced the jet in the carb and replaced the bulky airbox with a uni. Before the build I replaced the belt at about 2200 miles due to breakage. 400 miles after the upgrades The belt failed again. I realize the new found torque from the engine will add signifigant stress to the belt but 400 miles seemed a bit quick, seeing how I babied through the break in period. Planned on replacing the belt with a polini kevlar belt, just wanted to know if anyone has had any luck with this belt. Also plan on changing the variator, weights, clutch and clutch bell. Any recomendations on parts, part combinations, and part suppliers would be greatly appreciated. I'm not looking for extreme performance, just reliability with a bit more power behind it.
Thanks guys,
-Kyle

[90GTVert]

:welcome:

I've never used the Polini belt, but everything else I've had from Polini has been pretty nice. I can say that some cheap belts will snap faster, so I would certainly suggest getting a Bando, Gates, Polini, or something along those lines.

NCY and Naraku both make good variators. NCY even makes a whole transmission kit. Enviromoto.com sells them all and offers 10% off if you use the coupon code "49ccScoot' in Google Checkout. I have the Naraku and it's a good quality unit that includes all the pieces of the variator. Other members have purchased the NCY vari (at below $20) and seem to be pleased. I'd also suggest considering Dr. Pulley sliding weights instead of roller weights. They are more expensive, but they last longer and perform better. They seem to need to be about 1g heavier than the roller weights your scooter likes (if you use 5g rollers with good results, you will probably need around 6g sliders for similar results).

[kchart18]

Thanks for the quick advice, The trans is in dire need for upgrad, think I'll go with the ncy trans upgrade with dr. pulley sliders and the polini belt. Also saw the rear gear upgrades and was a little intrigued, saw somone posted they gained 10% top end speed with no acceleration lose. I find that a little hard to beleive, seems to me anytime you change final drive ratio your going to lose one more than the other. Does anyone have some ideas about that?
thanks,
Kyle

[90GTVert]

Never messed with them. Maybe if you use lighter rollers you can get the acceleration to stay the same, but it's hard to believe you gain both top speed and accel from a gear up on such underpowered little engines.

[kchart18]

Thanks for the insight

[sctrdawg]

Dude i took a 4 " angle grinder and cut a few vent slots in my cvt cover and my belts last a long time got a gates powerlink w about 3000 mi. on it and very little wear!!! I can ride 20 mi. and lay my hand on the cvt cover and not get burned!!

[jmkjr72]

i would look at the torque driver
i have seen a few clones that i worked on even stock snap belts often till i replaced the torque driver
also make sure your belt is running true i have seen some where the belt wasnt true and that can cause some issues too