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Discussion Starter #1
i searched the threads on here and they all relate to 09-10 xp850's mine is a 2011 with 10hrs on it. its been rode in temps from 20f-65f. it has always started easy but puffs alot of smoke then runs rich until warmed up. i just pulled the plugs and although not terrible they weren't perfect either. if its 20-25 out side and i start it it will blow black smoke then it lightens up in color. after a minute it stops smoking. it never stalls but will back fire once in awhile. im ready to give up and drop it at the dealers. my t-cable is smooth, the air cleaner is clean, and exhaust flows free. any suggestions?
 

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I'd tell your dealer about it when you take it in for it's first 20 hour service. They will change the plugs and if you will tell them your concerns they should also check your tuning and your programming as well and your valves on some models, though I'm not sure about these new 2011 850's yet.
 

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Discussion Starter #4
just found in my owners manual in the trouble shooting section that if you run to high an octane fuel it will run rich and/or poorly. Ive been using 91-93 pump gas does anyone think this is to high octance? I dont really know what i should be running in it.
 

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just found in my owners manual in the trouble shooting section that if you run to high an octane fuel it will run rich and/or poorly. Ive been using 91-93 pump gas does anyone think this is to high octance? I dont really know what i should be running in it.
Probably regular 87??
 

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87 octane. im not sure that a higher octane fuel will cause it to run richer, but poorly, yes very possible. the higher octane fuel resists detonation better then say, a regular 87 octane fuel. so vechicles with a higher compression ratio, such as some performance sports cars, and many motorcycles need to run on 91 or 93 octane, because if they ran on 87 octane, the heat generated inside the cylinder from the piston compressing in a higher compression ratio; the fuel/air mix could actually ignite on its own before the spark plug fired, causeing pre-detonation, which is very hard on the piston, and you lose a lot of power from the motor.

When running high octane fuel in a machine that doesnt need it, sometimes it doesnt ignite like it should, since it is formulated to be harder to ignite for the reasons just mentioned above. If it ignites late, or not fully, you will also lose power, very lilkely get backfires in the exhaust as unburnt high octane fuel gets put into the exhaust system, and the motor could stutter.

There is no benefit from running anything higher then 87 octane fuel in these motors in their stock form. You would need to custom internal motor work before you needed it.
 

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Discussion Starter #7
i only put it in my atv because the book said it had 11:1 comp ratio. I know in a street car that would be fussy on 87 octane. but ill switch back and see what happens. thanks
 

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just found in my owners manual in the trouble shooting section that if you run to high an octane fuel it will run rich and/or poorly. Ive been using 91-93 pump gas does anyone think this is to high octance? I dont really know what i should be running in it.
That`s your problem right there, these ATV`s arn`t tuned to run on 91-93 pump gas. it will run best on 85-87 pump gas
 

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Discussion Starter #9
I got a hold of one of the better dealers in my area. his answer was that im not letting it warm up long enough. he mentioned that his dealership has replaced the plugs in almost all xp's from his salesmen starting them and moving around there lot them shutting them down w/o fully warming up. Also i called polaris they said they would like to see all 850 xp's run on 91-93 octane. since the compression is on the high side. solution. I bought NGK plugs, fresh oil and let the damn thing warm up 3-5 min. before you touch the throttle.
 

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i never let mine warm up like that. I was told that when i first took a test ride on one at a dealer when the xp's came out in 09. Then came to find that they needed a hotter plug. That problem kept me from buying one in 09, glad i waited for the 10 anyway, much improvements on them
 
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