Burnt Piston - Snowmobile Forum: Your #1 Snowmobile Forum

nwicomputerguy · 12-26-2004, 12:57 AM

Hello,

Have a 89 Safari Escapade. I was told it is a 503 Rotax. Fried the stator side piston. Need info on where to get parts ect... Any info/tips will help.

Here is what I found after I did a compression test (0, 115). Pulled both heads. Tranny side looks good (115 too low?). I plan on honing/re-ringing it anyways. The fried piston had the top ring flakes scar the cylinder wall. The head has some metal flakes melted to it. Top of Piston looks like a black blob.

Can the cylinder sleve be pressed out, or do I have to get new cylinder? Can the head be machined to remove the metal? I can send pics if needed.

Also, I read from you experts - thank the Lord for you!! that it probably ran too lean. How do you test the carb for too lean and how do you test for leaks in the engine gaskets.

Again thanks in advance for any help

**smallengineguy** · 12-26-2004, 07:31 AM

The cylinder can be bored up to .020 over. Bring it to a shop and see if it's deeper than that. If not, you're all set. The head will probably have to be replaced. The fuel mixture won't "swirl" correctly wit hthe head all banged up. They are a dime a dozen used, a ton of machines had the 503.

When you put it back together, get a top end gasket set for it. That will eliminate any leaky gaskets you may have had. Although you will want to check the rubber boot that the carb mates to the cylinder with. When those crack that side will lean out. Biggest culprit.

DSMtuner · 12-26-2004, 02:29 PM

Im sure he could machine the head down if its barely knicked, but you would have to do the other one im assuming, as it would raise the compression in the cyl that got burnt. Ok, dont listen to me lol, smallengineguy is right. What happened sucks though.

nwicomputerguy · 12-26-2004, 03:49 PM

thanks for the info!!