Probably a lot cheaper to just bore and upsize the piston. Also keep an eye on Ebay for parts. I doubt you'll really notice any real power gains. I've found servicehonda.com to be the cheapest OEM parts place on the web. If I order something on Monday, I have it by Thursday, Firday at the latest. Not bad. When I did a top end on my brother in laws trx300 the cam chain was something like $80, $130 at the dealer.