Any good links for a top-end set? Are they the same as the 300cc set? Is there a difference between oem and aftermarket (thickness? Quality?) thanks in advance!

 

When I installed my 340 kit, the head and base gaskets were included from Thumper Racing. Honestly, I didn't look to see if the head gasket was any different from the stocker. For the rest of the gaskets, I just ordered a stock top-end gasket kit for the KLX250s. I got the gasket set from BikeBandit, and the brand was Cometic. The quality was very good. Give Thumper Racing a call about the head gasket.

 

thanks for the quick response- i'll try bikebandit.
I just got a 340 jug and a JE piston for $350 and I plan on selling the stock jug so I'll be spending less than $300 to go up 90cc!

 

+1. Definitely contact Tumper Racing on the head gasket. I'm not sure exactly how they do it, but their compression ratio is closer to stock...a little lower I believe. The gaskets might be part of the equation.

 

I can answer this one they have a thicker fire ring in the head gasket for lower compression.