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Old 03-26-2012, 11:29 AM   #1 (permalink)
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polaris 800 engine problems

i have 4 2010 polaris 800's all with less than 500 miles on them. 2 have seized pistons, one was a failure of both pistons, the other one had only one go down and a third one with constant overhead problems.

the first seize was after a 5 mile ride, shut down for an hour, then start back up, ride a mile in soft snow about 4 feet deep at about 30 mph. the second sled was going down hill on a trail when the piston went, both lean seized. the third sled can overheat at weird times like going downhill with a 100 lb rider (why not uphill? - tho it can do that as well) talk about gunshy and gutshot... just waiting for another seize. the dealer says put scratchers on, which i have... that doesnt really instill confidence. these sleds should be able to motor down any trail under normal circumstances and not blow to pieces... whats going on? we run premium fuel, put polaris fuel conditioner in it, run pure polaris premium oil and no one is fat. these sleds arent being pushed at all.

i have 2 polaris 600s that are 4 years old and they are bombproof.
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Old 03-26-2012, 01:11 PM   #2 (permalink)
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Don't run premium unless the engine has had some kind of mod work to raise compression. You can actually cause preignition that way. Are these sleds EFI? If not, I'd try going up in jet sizes by 10-20.
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Old 03-26-2012, 02:00 PM   #3 (permalink)
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all are EFI - and have been re-mapped to the latest and greatest... supposedly so that you dont get a lean seize. so re-jetting not an option. an expensive option would be to ditch the efi and put on carbs. also, polaris manual states premium fuel. we go by the polaris rules. premium fuel retards predetonation - and according to the polaris mechanic, none showed signs of predetonation, lean seize on the bottom of the piston skirts, not on the top.
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Old 03-26-2012, 02:34 PM   #4 (permalink)
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Are you using oxygenated fuel?

Polaris has had a lot of issues with the 800, but dang.. I would sure think that they would have it figured out by now. One of the guys I ride with has a 2010 800, it's got a turbo on it and he has had no issues. Have you considered adding a fuel controller to increase the fuel in the midrange? The Polaris map is on the ragged edge to keep EPA happy, you may be able to add some fuel to keep your engine happy. Just a thought...

I had a problem with a Polaris sled overheating and after a bunch of overheating (two that resulted in seizures) I finally took the water pump housing off. The nut that is supposed to hold the impeller on was in the bottom of the housing. When the engine idled, everything worked as intended, the pump impeller was able to flow enough water to keep everything cool and to heat the rear heat exchanger. It felt normal. But when RPM went up, the shaft turned inside the impeller and hardly any fluid was being moved, so the engine would overheat in about a quarter mile. It may be worth a look. I have not heard of any of the small block 800's with impeller problems, but who knows. If the system doesn't have air in it and coolant is fine (check for ratio; if it's 100% antifreeze, it won't cool as well as a 50/50 mix) and snow is hitting the tunnel, it should run cool. About the only thing left would be the pump.

I hope you get it figured out, it sucks not having reliable sleds. The Polaris small block 800 is why I ride a 700. And I agree.. the 600's are VERY reliable.
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Old 03-26-2012, 02:40 PM   #5 (permalink)
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ya - all the fuels here have some kind of ethanol/oxy adds. the water pump is one thing that we have considered but not yet checked. after this week, perhaps we will know a bit more. sucks to be in this condition.
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Old 03-26-2012, 02:44 PM   #6 (permalink)
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You said you got the mapping update...has the oiling issue been addressed? I think there was a dealer update for an additional oiler for that motor..?
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Old 03-26-2012, 03:10 PM   #7 (permalink)
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both sleds that burned down had sufficient oil both on the crank, rod bearings as well as on pistons and rings. had 2 mechanics look at it, a polaris mech and a custom sled shop - both said lean fuel seize. both gave similar advice - dont run the sled for any period of time at constant throttle - keep moving it up and down, at least a little.

as for the fuel - the polaris fuel additive is supposed to help with the oxy fuel-ethanol issues and to be fair, we havent burned one down since we started adding the fuel treatment... the overheat is still a weird problem.
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Old 03-26-2012, 03:20 PM   #8 (permalink)
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Just another thought.. when were the fuel filters replaced? Clogged filters could also contribute to lean conditions in the EFI. Those fuel filters are spendy little devils!
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Old 02-09-2013, 08:49 PM   #9 (permalink)
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Hey, I wanted to add to this. In the last few years my family has purchased 4 new polaris Rush's. 2 600's and 2 800's. we ride about 2000 miles a year on each sled. So far each sled has nuked an engine in the middle of its 2nd year. One of the 800's is new this year and ok so far. It seems that all of the new fuel injected polaris snowmobiles have a big lean problem.

We do all of our riding in the upper part of Michigan where 90% of our riding is constant throttle. We have changed to racing oil and adding fuel supplement per the dealer on every fill. Obviously federal emissions are killing the 2-cycle engine from what I can see. We want to be able to ride our machines, 8000+ miles like we always have.

Doing some type of tuner sounds great but how user friendly is this to the average joe? These sleds are fuel injected. I believe they will require slightly more fuel to solve our problem. Where do you obtain this type of equipment?

Chris
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