I have a 97 XC 600 and it runs like crap. When i hit the throttle the engine does fine until it hits a high rpm then it bogs extremely bad. if i let off and get back on it, then it bogs at an even lower rpm. i have checked the fuel system and its fine. i talked to one of my buddies who works for polaris and he thinks my piston rings might be fried but i don't see how that could be it. if you know anything about this please help.

If your fuel system is indeed fine... then I would say crank seal or crank bearings. If the rings where screwed it would more than likly just shut the motor down and not start again. easy way to check the crank seal is to start the the sled and then spray some carb cleaner on the case in various spots to see if the motor revs up. As for the bearings im not sure there is a clear cut way to tell exacly if there bad short of having shaft wobble or pulling your motor apart.

It could very well be a fuel starvation problem. Crank seals (from what I've learned) won't let the engine idle or low RPM function properly. If I were in your situation I would have a good look at either the main jets or the fuel pump and filters, Including the in-tank pick-up screen. It sounds like something is restricting fuel at WOT.

Do a compression check, then you can rule out the top end of the motor. Then obviously spray the seals with ether. Also, take the carbs off and take a look at the piston skirts. These are important for port bloacking and if they aren't there you could be running extremely lean and may have other issues as well.

this bogging isuue you are referring to, is it while you are riding? or while the sled is on a stand?


Sounds like a clutch binding if it is happening while riding. but this is very hard to diagnose problem without actually seeing the sled.

My 97 XC was very hard on clutches. When is the last time you serviced yours?

Sounds like a fuel pump to me. Somthing isnt getting gas in there at WO..

tighten the seals on the front of carbs.(the rubber boot with clamps on front of carbs). worked for me.

I had the same sled a couple years ago and it gave me the same problems, and it ended up being the clutch...to test this you may just wanna put it up on a stand and see what the clutch does for movement when you give it gas. If it's the clutch though not only will you get a power loss, but ur gas mileage may not be very good either, seeing as everything is pushing so much harder to move the sled.

my xlt was doing that for a while but after i put a new fuel filter onit and my pipes on it (aaen triples) and rejeted and did the clutch work it stopped doin that so i just figured it was the fuel filter

My question is, is it truly a bog or is it just dropping RPM? Bog would deffinatly be a fuel starvation problem, just dropping RPM could mean your sucking the secondary open (weak or broken spring)

Im with BuddyP on this one!!
A worn or broken secondary spring could definately be the culprit! Especially at high speed or top end of operating RPM.
It could also be a combo of things I.E. Worn spring, worn helix buttons, worn drive belt.