Iv raced one. I dont remember any times or speeds. Hauck powersports sells a good primary spring for the stock yamaha clutch. I also put in thin copper head gaskets to bump up compression. Stock gearing worked the best. I tried dropping gearing down. What a headache with clutching. As Tony said about skid set up. Good tight springs in the back. Also after market reads with jetting. That sled ran pretty good. Aaen sells a race pipe. Never got one. Hope this helps??