I have a 1987 and a 1988 skidoo escapade 503. Two weeks ago while out riding for about an hour. I blew a piston on the 88 sled clutch side. Have all the parts just need to put it back together. This weekend we were riding the 87 for about an hour and bang.. there goes that sled. Blew the piston in that sled to. Both clutch side. Someone told me it is the gas we burn today with the ethanol.. I dont know if this is true or not. But does anyone have any idea what could have caused this to happen in two sleds.. we were just trail riding not lake racing or anything.

Thanks

I would say its just a bad timing coincidence. Depending on how many miles are on the sleds they might have been due for a rebuild anyway, being as they are 20 yrs old. There are lots of factors to look at when you pop a piston. And fuel will have a bit of an effect, but not a negative one unless its got water in it. Ethanol burns a little bit hotter and somewhat cleaner, but doesn't have as much of a "bang" so I usually try to stick with gas that doesn't have a high ethanol content. I use Shell and Esso only. Hope this helps.

Sounds like seals to me

Common causes of piston failure include plugged/restricted fuel flow causing lean conditions and in the case of fan cooled sleds running them hard in mild temps.

Were your sleds properly serviced?

The 503 is a great engine not known as a piston eater. The causes for piston damage are numerous so know why it blew before repair. Check the exhaust outlet on the side that blew if it is grey/white that suggests a lean condition possibly dirty main jet or air leak. What kills most 503 motors is a loose fan belt... Sanford