Hey guys, I have a Yz400F motor in a quad frame and its not stunning. Its not bad, considering it was replacing a XR400 motor but Im looking for some more grunt. Ive researched a little and found that they make a 417 13.5:1 kit. The kit was about $600 and was a new piston and cylinder. Also, they sell the 417 piston alone. Im wondering if you can bore the stock cylinder and re nicasyl to accomodate the new piston. Ive also heard that a 450f cam is a good idea, with the auto decompression and a gain in performance. Can you go with an aftermarket 450 cam with the stock decompression device? Lots of questions, I know. Im just looking for a good motor setup. I considered just getting rid of the motor, and starting with an electric start yfz450 quad motor also. Im kinda in the research stage now though. I figure adding some cc's and compression, porting and cams would make this a strong motor. Im lookin for somethin in the 50hp range... Let me know what your opinoins are.