[Rodznreelz]

I have a 2001 Evinrude 250 FICHT. I just rebuilt the engine after losing compression on two cyliinders due to overheating (trash in the thermostat). I bored all six holes, new wiseco pistons, etc. Got it back together. Went out on Sunday and after about an hour of running, I burnt a hole in the #5 piston right at the exhaust port. Plenty of oil in the cylinder that burnt. Any ideas on what happened?

 

[Sequoiha]

Did you ever determine cause of original failure? Sounds like an injector issue

 

[Rodznreelz]

The first time it was rebuilt was due to it overheating on the top two cylinders on the starboard side. I found a piece of plastic on top of the thermostat, which I assume wasn't allowing the thermostat to get up to temperature. This time, I don't know.

I have been told by a few people that it sounds like an injector problem, but how could running lean cause it to burn a hole in a piston?

 

[The Maintenance Shoppe]

I would have to 2nd the bad injector theory.