CM1200-1026 , CM1200-1028 , CM1200-1027 NCY Compression Spring (GY6), Black 1000 rpm Yellow 1500 rpm Red 2000 rpm $14.99 Shipped in the US. Compression springs do a couple of things. First they supply the pressure to engage the belt. They also determine the rate at which the CVT transmission changes from low to high gear. A 1000rpm spring will go into a higher gear than a 2000rpm spring.