Help with 82 kz250

Shove that ring all the way down the bottom of the cylinder see what the gap is there and subsequently, discover what the cylinder taper looks like.
It looks to me as if the cylinder is damaged badly and you'll need a new piston at least a half to one millimeter overbore.
Pictures are not the same as holding it in your hand though.

I agree that cylinder looks like it has some corrosion, and a few nasty spots near BDC... did that bike sit unused for an extended period of time? Another clue would come from the air box, if it looks like there is oil in the bottom of the air box where the crank case breather line is connected that would indicate blow by. From your compression measurements and the looks of that cylinder you should have had some significant leakage into the crankcase.

Measure the cylinder using the method described in the manual, this will give you maximum, minimum bore diameter, out-of-round, and taper. IF any of those readings are out of spec you need to overbore. Trying to find new engine parts for that bike may be very challenging, so you may need a donor engine or resort to refurbishing used parts.

We can't tell form pictures, only the proper measurement can direct you. You may be able to hone and re-ring it, you may not. If you can get a close up picture of the stained areas and the funny marks near BDC on the cylinder that would help. The 250 is very under stressed engine, something like 18 to 20 hp. The ring gap could be larger on purpose, the factory service manual is a necessary purchase at this point. I owned a 81 kz250 for close to 15 years, never had the engine apart though. They are a neat little bike.

missionkz wrote: Have you had a chance to check the compression ?

Thanks for pointing me in the right direction

Thanks all for the help. After I re ring it I'll get back to everyone

Looks like rust staining at the top and in the middle where the rings sat, Condensation can do this. If so a over bore will be needed.
Steve

Hey everyone I got the bike back togeather. Now I have a no spark problem
I bought this gasket set is the same as a kz250. The reason I bought this one is because the kz gasket was way

more expensive for some reason

Thanks again everyone...I got the bike running today an she runs great

COOOOL !!
Pete