WR400 rebuild

Hi all, I just found this site and have some questions.

I have a TZ250 chassis, yamaha 426 motor hybrid roadrace bike. I got a WR400 motor in pieces along with the bike. The previous owner said the 400 motor needed a crank assembly, piston kit and the cylinder resleeved. Is rebuilding this motor something I can do or should I have someone else do it? If so, who? Also, what else should be checked/replaced during the rebuild? Should I bump it to 420cc? Where should I get the parts?

Also, what should be checked in the 426 motor as preventative maintenance?



I highly recommend you have a profeesional rebuild her. valves and valve seats, cylinder boring and coating are not for your average garage mechanic.

You can take it all apart and send the head and jug out but the crank is a pain to get back into the cases! Have a pro do it if you can afford it. :)

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