I have a bike and it has a 6HP race motor from Jakes Custom Motorbikes all polished and ported with a notched and skirted piston, Diamond High Compression head, Mikuni VM18 carb, 40 tooth rear sprocket, Rocket Raceing CDI and a expansion chamber exhaust. My first rude was 10 minutes and not much power. 2nd ride it had more power and pulled hard and good throttle response. I am on the third tank and it tops out at 30 mph. I use ready mixed 40:1 stuff from Lowes that is equal to 92 octane and ethanol free. I feel that I should be at least hitting 35++ mph. I see stock motors doing over 30mph with a 44 tooth sprocket. I just bought a Suzuki RM80 expansion chamber and a KTM 85 silencer. Any comments or tips will be appreciated.