Piston Melted on Cylinder

[Old-rider]

Just put new top-end on 99 KX125 (cylinder, Weisco piston, ring, small-end bearing). Although I thought the motor was properly broke-in and warmed-up for this ride, on the first ride at over half throttle the bike did a "cold seizure" after about 1/4 mile down the road. The new top-end probably has about a total of 2 hours of break-in running time. I have torn motor down and see that the piston and ring are toast, but new cylinder only looks to have aluminum from piston on it. I used a scotch-brite pad and oil to clean the aluminum off of this new cylinder. I used a side-ways stroke in using pad on cyllinder although admittedly I do not not what is meant by cross-hatched honing.

Should this cylinder now be OK to use again? Any other precautions advised? I am planning to this time use a stock Kawasaki piston rather than Weisco as I understand less prone to seizure.

 

[Studboy]

If it was broken in and warmed up it doesn't make any sense that it would cold seize. Maybe the piston/bore clearance was incorrect i.e. oversize piston or something happened to make it run lean. The cylinder should be find as long as the plating didn't boil or peel away from the aluminum. Just look everything over before you rebuild it because if it was warmed up it shouldn't cold seize. I'm guessing either a lean jetting issue because of the cold, an air leak, or some junk plugged the jet in the carb.

 

[smahala1286]

forged pistons sometimes cause cold seziures when not properly warmed up or broken in.

 

[gowen]

forged pistons sometimes cause cold seziures when not properly warmed up or broken in.

Sezco, I've heard it for years. But to be honest I've run Wiseco in everybike I've ever rebuilt for the past 10 years and have never had a cold seizure, and I am never that patient on warming up. Something is up if it froze up, eg serious lean jetting or incorrect clearence.

 

[YZ165]

I'm with gowen. Something is amiss.

 

[smahala1286]

Sezco, I've heard it for years. But to be honest I've run Wiseco in everybike I've ever rebuilt for the past 10 years and have never had a cold seizure, and I am never that patient on warming up. Something is up if it froze up, eg serious lean jetting or incorrect clearence.

yea i have just heard it on this board that some people have experienced cold seziures, but i have heard more good about forged pistons than bad and for my new rebuild engine there is a new wiseco piston sitting there ready to go in. I agree there probably is something wrong like jetting or something i just wanted to list all the possibilities.

 

[WillyM]

Aluminum on cylinder

I have a good way to get aluminum off the bore, use muriatic acid on an old tooth brush and it will scrub right off .
keep away from the ports but in the bore it works verry well.