I hope there are some on here who remember the old stuff. 1974 GPX 338 with stock primary clutch and stock secondary. What primary spring should I use to get my engagement up to 4000-4200. I know I'll have to adjust y secondary but I need to get engagement up to get into engine power band. Currently it engages at 3600-3800, Depending on how fast I rev it up. It has what I think is a stock spring with a shim washer. I'm guessing the spring is wore out. I would like to race sled in pure stock vintage drags.
Yamaha Nutz
New member
yellow/white from a 76 ex 440 should do the trick part # 90501-55403-00