evinrude 300 xp melted piston

[brianja27]

I just purchased a checkmate with a evinrude 300 xp. Boat sat for 5 years. I did a test run on it everything ran well got it home put it on the water lost all power got it home and discovered one piston was just melted plugs also melted question is what could have caused this and is there a problem with just sleeving that cylinder and replacing that piston thanks for the help I'm new to these go fast out boards

 

[Joe Reeves]

Re: evinrude 300 xp melted piston

Melted piston is due to pre-ignition, usually due to a clogged, fouled, lean running carburetor OR a very small water spray entering that cylinder to name a couple causes.

Re-sleeving or boring just one cylinder is fine if that's the only damaged cylinder but the entire engine needs to be torn down to do that work anyway (major overhaul).

 

[brianja27]

Re: evinrude 300 xp melted piston

Thanks for that what do you think of after market heads on that it has them now but I have the stock ones don't know of that could add to the melt down idk the brand but they have 2 plugs per cylinder along with two coils