Posts
17
Joined
3/7/2024
Location
Collinsville, IL
US
recently rebuilt 04 ktm 125 bottom and top. The engine has less than 1 hr on rebuild. squish is set correctly and had a local guy check ring gap, check exaust porting, and tune carb to make sure it was correct. He gave me the go ahead. the cylinder was sleeved by la sleeve. Looks like a lot of scoring on exhaust side of cylinder. Curious what people's opinions are, is it just the coating wearing off the piston. Something else? Do I need to pull the head & cylinder off then rehone? also noticed the discoloration on the top of piston right at the exaust side. This is my first bike and I'm new to all of this so any help is appreciated.
That piston looks REALLY clean and I would pull it apart to get a real look at it. The clean piston shows a lean condition IMO and would contribute the scoring.
In general, a clean piston top suggests rich. Baked carbon extending to the cylinder wall suggests lean. This is called ‘piston wash’.
Ahhh yes you correct My Bad
Sleeve is not the way to go. Looks like it detonated but it's hard to tell. It definitely got hot. You may be able to get away with a hone. but unless you get your jetting fixed it will just happen again.
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