1999 KX250 pinging

[pkbarbiedoll]

hi I bought a 99 kx250 recently.  it seems to be in great condition and came with a tank full of race gas.  but it pings under lots of throttle, mostly in the mid range.  if I don't open it up too much it doesn't ping at all.

So, would I need to lower the needle clip first?

[alan]

Pining is detonation, which means the octane is to low and it could be that the fuel is old which changes its octane. You would raise the needle one notch at a time to richen the midrange.

Welcome aboard!

Alan

[KXcam22]

Allan is correct about the detonation.  I would also check your main jet size and compare it to stock. It may be that the previous owner leaned the bike out too much.  Cam.

[eprovenzano]

Congratulations on the purchase, and welcome to the forum.   If you have any questions this is the place to get answers.  The forum members are very knowledgeable and always willing to help.

I too have a 99 KX250, its a great bike, very dependable. I agree with Alan and Cam, it sounds as if you have jetting issues, running too lean.  After you get the jetting sorted out, you will love the bike. 

Let us know what you find.

[gowen]

What type of race fuel does it have? Old fuel is a issue, but even with old fuel it shouldn't be too bad. On my KX it pings too, even jetted. It's pretty normal. It usally is a sign that is isn't being ridden hard enough.

[air]

Drain the gas and go get some fresh gas with oil mixxed the way you are going to be mixxing it and go from there