I recently purchased a used 2003 YZ250. After a couple of rides I decided to pull the top end for an inspection. I discovered the top of the piston was damaged as if the bike had broken a ring at one point and the pieces got crushed between the piston and head. Apparently the pervious owner threw in a set of rings and put it back together. I've seen this type of damage many times. However, in addition to the small craters, there is about a 3mm band around the top of the piston that looks like the piston was actually melting. It's not just one spot, its all the way around. I've never seen this before. Does anyone have an idea what might have caused that kind of deterioration?
YZ250 Piston Melting
- Thread starter YZDriver
- Start date
It's the result of detonation. You have serious tuning issues that you need to resolve.
