They may be a step or two backwards, but you can use them. 30mm 1:10 taper flush mount bore. I am personally in a situation where I can either spend $800 on rebuilding the original yamaha clutch, or try to find a used one for a deal, or use a clutch I have sitting around from a cat or polaris or a comet. Yamaha uses a good clutch, but starting from scratch I am gonna go cheaper.