Primary spring chart
#16
#17
Primary spring chart
Scrambler123, the numbers are how many pounds it takes to compress the spring down to the stated length. The first on the list takes 5lbs to compress to 2.5" and 117lbs to compress to 1.25". This dictates the engagement rpm and shift characteristics (along with cams and weights) of the primary clutch. If you want more info, it would be best to aquire a clutch tuning manual.