whats the score with oversize pistons? my kx250 compression is not what it should be, there isnt any heavy scoring, the plating looks even and the heads fine. the bikehad apiston stamped "A". i replaced that with a new piston stamped "A" which did improve compression but still not what it shood be. should i purchase an oversize piston (if so "B","C" ect....how can u tell?)or should i replate? i am fairly new to the scene and appologise if anyone hurts themselves laughing at my ignorance. [>:]

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its alright, it took me a couple months to grasp the whole oversize thing
if you want to get an oversize piston you need an oversize topend. you can buy a borekit or order a combo Btopend and Bpiston or Cpiston and Ctopend etc...

or if you want to save $ and just solve the compression id just get the cylinder replated or just resurfaced.

then theres the "duh" answers we usailly dont realise until several hundred has been spent. have you replaced your gaskets lately? what shape are your reeds in? exhaust springs holding their tension?

if you know how to check theese things, do that. if not ask and i can help you out,... and if i cant someone elese will we heav alot of gearheads here.[8D]

 

Had the same problem with my old 92 KX250. Ended up sending the cylinder out to La Sleeve to get plated. Solved the compresssion problem for $ 300.00. Included matching piston and top end gasket kit.

 

re-plate it is then, thanx for the info!