77' Evinrude 140 - Piston Ring Failure

[GeauxCajuns82]

A few years ago I took my boat out for the first time that season to do some skiing with friends and it had a noticeable lack of power. Took it to a mechanic a few weeks later and they said the bottom left piston had half the compression of the other 3 and the motor would need a complete overhaul for the bargain price of $2k so I just took it back home and disassembled the motor. Turns out one of the piston rings in the bottom left piston/cylinder shattered and some pieces even made their way into the combustion chamber. There is one small scratch in the cylinder wall as well as several small divots/gouges on the top of the piston as well as the cylinder head. So now I have the following questions:

1. Is this a common failure for motors of this age? The only previous owner was my uncle who probably ran the thing once a season, if that. The motor probably has less than 100 hours on it
2. I had run the motor dry before putting it in storage for the winter but never winterized it, could that be the culprit?
3. Is it possible to only bore out the damaged cylinder and replace only that piston or do all 4 need to be bored out and replaced?
4. Can I reuse the cylinder head? I can't find any companies that sell a replacement for that model year. MarineEngine.com has the cylinder head available for the 140hp but only for 78' and later. Would this fit on my powerhead? If not, what changes were made between 77 and 78?​

Any input would be greatly appreciated.

 

[cdn-pk]

Re: 77' Evinrude 140 - Piston Ring Failure

first you should never run a 2 stroke motor dry (no fuel = no lubrication). if you want to drain the fuel from the carbs use the drain plugs. and you should fog the cylinders with fogging oil.

i believe you can bore one cylinder and replace the piston (with an over sized) provided you can get one that is properly balance (with the others)

sound like you heads are fine just need to be rebored.

the 78 model year the design changed not sure about power heads but have messed a bit with lower units (i had a 77 140hp for a few years) so i doubt a 78 head would bolt on