I have a 98 yz400 that i got for free. Yes, free. The only thing good about this story. Anyways... So long story short, I tore the bike down completely to rebuild from frame up. Motor was ran for a while with a blown head gasket. So the top end is apart, I had heard rumors that I could run a 450 piston in this thing inside a 426 jug. I have a boat load of parts for this bike, literally 99% of what i need to have this thing brand new. I just need your help with the last 1%. I have a new top end for a yz400, have a top end rebuild for a 450, and I have a new jug for a 400 plus another for a 426. What are my best options?? I had to have the surfaces decked on the stock clylinder beacause of the damage from the blown gasket. I was told im going to need to run two head gaskets now to compensate. So basically if anyone could give me advise or input on this process/ anyone done this before? P.S- Im having trouble getting my hands on new copper washer/ ring things for the oil lines can anyone help me find these?