I havent found a definate answer yet. I'm building a 2000 400ex into 416 and need some pointers. I bought the bike cheap (blown up) and have a little money to put into the motor. I wanted to make it into a 416 because reliability is my main concern, but I don't want to run race gas through it. Shell's V-power 93 octane gas has been good to me in the past and I was wondering if I could run 11:1 compression on 93 without detonation or would I be better off to go with the 10:1 piston. I've heard that a 10:1 416 might as well be a stock 400. I have to replace the sleeve anyway so would it be better off to just make it back into a 10:1 400. I'm also at a loss for the cam and jetting setup. I've heard a lot of good about the 450r carb but if i go sticking too much money into this I would be better off just getting a 450r. OPEN TO ALL SUGGESTIONS. Thanks!!!!