[sodbuster69]

this aint right, quads cant touch me but a xr650r and yzf 426 (stock as far as i know) are woopin me I would like some expert advice on some engine mods i got fmf pipe, boysen super stock valves, 1 mm over piston w/sleeve, 91 gas with klotz oil (20:1)and octane boost. the xr says i am quick till 60mph then slower til 80 where i top out. I would like to get more top end power. my idea right now is to port a little to match the new liner to the cylinder casting, and maybe two base gaskets. The internals do look good after the rebuild, so i think its jetted good and mixture is ok. But i need more two stoke advice for what really needs to be done to beat these guys.

[Quick 26]

wow if 80 is all you are getting my little quads will wear that thing out.

you need to pull that cylinder off and have it ported by a profesionall and send the head off with it to have the chamber reshaped, or buy a cool head with a CUSTOM cut dome. what carb are you running?

[johnnycrash]

A decent running CR500 should S-M-O-K-E a YZF426.

Like Quick said, you need some porting. I'd call K&T in Utah - they did my two smoke Honda and made it scream.