Quick question. Rumor; kx 250 head gaskets are thinner than kdx250. If this is true, what years will swap over to my 91-250. If you have done this would you tell me if it gave more power and if it started pinging more.
I always ordered one for an '88 KX250, but have heard that '88 - '90 works. It should not ping on pump premium with the thinner head gasket. Higher compression should give you more power everywhere, probably most noticeable at low rpm. Since I never used the stock gasket, can't really say for sure how much more it adds.
I use a gasket for a '90 KX250. The head gasket is thinner, boosting compression. It is not a huge difference in power, but it did give mine a little more snap. When you rebuild the engine, you can use a Weisco piston for a '90 KX also, part# PS-90.
You asked if it would ping MORE? Does your bike ping now? I have never experienced pinging with my bike, even though it is far from stock. If your bike is pinging, you have a jetting or timing problem, or you are using gas with too low octane.
I've got most of the same mods spanky and the 90/91 kx piston from wisco is the same part # as the kdx. I was asking about pre-ignition only because higher cylinder pressure with our crap pump gas can lead to pinging. I can make my 250 knock when hill climbing WFO, particularily out in the sand dunes after a long sprint. Our Nevada desert eats up many engines but gawd its fun! Actually ordered an 88kx head gasket today along with a pro lite. Thanks for the response.