95kx250

Joined
Sep 9, 2002
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#1
I have a 95 kx250 that needs the cylinder replated. My compression is all the way down to about 118psi. I was told that was a pretty low reading but never found out what the actual psi should be. The bike starts pretty well and seems to make decent power but i think it's lacking a bit I was thinking of having it bored to a 265Big bore. There isn't going to be any porting involved, i was only going to install a v-force after i got everything back. Is there a big power increase throughout the rpm range and will it effect my compression ratio and jetting. I run a 13oz. flywheel weight and have a Gnarly pipe on it now. Other than that the bike is pretty stock. Does anyone rememeber how much horse power this motor had stock compared to the 98kx250's and up,just curious. Any info would be appreciated Thanks.............
 
Joined
Aug 1, 2001
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#2
You may THINK that no porting is involved, but that would be an incorrect assumption. Boring out your cylinder WILL change your ports. Think about it.....your ports do NOT come in straight from the sides....they come UP into the sides of your cylinder. When you do a bore job, you move the point where the port enters the cylinder DOWN the cylinder wall. This changes your port timing. Whether it moves the power band up or down the RPM curve, I don't remember. But talking to a knowledgable engine builder (like Eric Gorr) will tell you and you can decide then if you need to have your ports done to bring them back to original specs or if you need them changed totally to deliver the power you want.