engine damage - need advice please

[djp2k3]

I picked up a used 03 kx125 last year spring. The first time I changed the top end, I noticed the cylinder was pitted from detonation I guess. It is all around the inside top of the cylinder, above the ring seal. Just the inside edge, maybe an 1/8th inch wide at most. I've been riding it as is and it seems to run strong, though It's been a real pain to get jetted properly. I'm wondering if the damage is causing any performance issues or should I not worry about it since it is above the ring seal? Any suggestions would be appreciated.

 

[nickyd]

no worries - its a ridge of carbon if I'm understanding you correctly

 

[djp2k3]

It's not carbon. The cylinder is actually eaten away. Pitted.

 

[marcusgunby]

You need to worry about it, eventually the piston and cylinder will fail, the 03 needs the pilot to be really leaned out, you have to drop it to at least a 35 pilot.Then you need to consider running better fuel.