Gates C12 as well. Cost and availability was the reason. Coming from the Kawi world, we swore by stock belts. Had the OEM belt start to delam so tossed in a C12. Beat the living snot out of it with minimal (okay maybe 2 miles) of break in. This includes woods riding, dusty Oregon trail riding in hot weather, hi speed runs thru whoops, short course racing, and a brutal day at the dunes where we just aimed and hammered the skinny petal - and in many cases never planned on actually making it up what we were climbing. After at least 300 miles I pulled it out to deal with an STM clutch issue - belt looked like new and will go back in.
But a few belt prep tricks we learned from some old timer MTEG Oddy racers when my son raced Trophy Karts ... Remove belt from package, wipe off edges with lacquer thinner / contact cleaner to get all the oily residue off. Lightly sand the edges, wipe off again. Lightly scuff the clutch sheaves and wipe clean to remove belt residue. Install belt and run for 15 mins then let fully cool. Remove, wipe clean, re scuff, re clean then drive it like you stole it, no easing into the throttle, do not bog it. We often prepped several belts. Heat kills all belts. Do not store in the cardboard shipping sleeve - let it assume a round shape. Store spares in a black plastic bag in a cool dry environment.
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