2001 Polaris

[BAKERMAN]

My 2001 550 air cooled polaris with less than 1000 miles on it decided to quit on the trail yesterday...no warning or anything....took it to my local mechanic, he says the piston is gone....cannot figure why....the oil lines were full, everything else seems right....have any of you experienced this issue? Also should I be concerned that this can happen again...is it time to trade it in and get a new one once it is fixed?

Thanks for your thoughts

[DEADhead]

sorry to hear that happened, but it's not the first time I heard of a problem like that with the 550 fan cooled motor. cut your losses and update to a modern EFI liquid cooled engine. they have more power and you'll be glad you upgraded. I know a 4-stroke isn't for everybody but I'm real happy with mine, and will never own a 2 stroke motor again. Good luck!

[BAKERMAN]

Thanks Deadhead.....one question, How about the weight difference when you convert to a 4 stroke....are they harder to handle in deep snow(when we get some here in minnesota)? I am not getting any younger or stronger so I am concerned about this weight issue...

[DEADhead]

the weight on the four strokes have come down quite a bit in the last few years. on most of the new sleds they are only marginally heavier. if you go the turbo route, you will have every bit as much power as a two stroke, if not more. The one thing you will not be doing with the four stroke though is tipping it on it's side. Unfortunately I rolled my sled this morning in a ditch and now I need to crank the excess oil out of the spark plug holes. the oil made its way in to the air silencer baffle. I guess it's all part of the game when you play in the deep stuff

[hanson]

The biggest enemy of a snowmobile engine is heat. If you can't cool your sled off, you'll smoke a piston in a heartbeat. There is a possibility that your sled wasn't getting enough cooling although with the temps we've been having, I wouldn't suspect that as a culprit.

Another surefire way to burn your engine down is dirty carbs or carb. If you did not clean the carbs this year, that would be where I'd start looking. A dirty carb will lean your sled out causing it to overheat and boom! You'll typically diagnose a dirty carb problem earlier since your sled will be running a little rough.

[ChuckN]

Unfortunately, I've read online from owners and talked to mechanics that say that the Polaris 550 fan model is fairly susceptible to these issues.

One mechanic I know repaired a blown piston with hardly any miles on the motor, out of warranty...took it out for a test drive before the customer even picked up the machine and a piston blew again. Frustrating to say the least.

IMO, I say trade it.

[Macgyver55]

Without looking at the piston personally its difficult to determine exactly what caused it. It depends on where the piston is damaged. If the piston was damaged due to a "scoring" condition make sure to clean the carbs at the same time you repair it. A slightly plugged main jet can cause a scored piston. It may still "feel" like it is running right most of the time but adversely affect the engine when at full throttle. A needle that is positioned too low can also burn a piston if running for extended mid-range throttle. If it was scored, after replacing it just to be safe I'd lower the needle clip 1 notch (which will raise the needle and slightly richen the mixture).

If the piston was damaged on the top surface around the edges, it indicates a detonation condition.

[ChuckN]

Yep, what Macgyver said. A good mechanic should be able to diagnose the cause, or at least I hope so.

[BAKERMAN]

Thanks to all of you....it appears that the machine overheated basis my mechanic...he will rework the carb and is looking at the jets....hope this is not one that has an ongoing issue..just looked at a new Polaris 4 stroke,,,,$6000 plus my 550 out the door...may keep the old one for a while ..Again Thanks for all your help