I just picked mine up yesterday, did not know about the problem with ethynol in almost all gas. I put premium in on the way home on the trailer and the engine icon came up on the digital readout. It means faulty EFI and do not ride. I talked to some service people and ethynol helps create some kind of water in the fuel and a local dealer had some STAR TRON which puts the correct enzymes back into the gas with ethynol. It is running like a bandit now and thought this might help someone else. The dealer I got it from did not tell me about the gas thingy.

 

Ethanol has a different stoich point than gasoline. Since these machines do not have O2 sensors to adjust the air/fuel mixture ethanol can cause a lean condition,how severe depends on the mixture. Gasoline is 14.7:1, E85 is around 9:1 IIRC, but I would imagine your fuel is a 10% mix so it isn't as drastic.
So another way combat this a higher octane fuel needs to be ran, ie the 08 800 calls for 87 octane gasoline and 89 oxygenated.

 

Congratulations on your purchase westpointdawg! So, what should your run these machines on, regular unleaded or premium?

 

I run my scooter, Nissan 350 Z convertible, my deceases wife's '02 Pathfinder, mowers, blowers, and chainsaw all with high octane fuel and have never had problems with any of my engines. This is what will be put in the XP and it is running like you would not believe after I put the STAR TRON in the fuel, only 2 oz. per tank, and can use 1 oz. per tank now that I have the hoss running good.

 

Ironbear-The 850 is no different that the older machines for fuel requirements,they have always required higher octane for an ethanol blend.
Personally though I'm not real comfortable running 87 in an engine with 11:1 compression. Polaris must have the ignition advance very conservative. Which if that is the case is nice because with a tuner that could bump up the advance and some higher octane fuel,say 93,a nice power gain could be seen.
With the 800 and it's lower CR I ran 87,in the 850 I run no less than 89. Too high onctane does no good but I think with that CR, 93 would not be overkill. A little too much is better than not enough. If you ever load the engine and hear it rattle then you know you don't have enough octane. But you don't always hear detonation and it can destroy pistons fairly quickly.
It also depends on how Polaris rates the CR, is it static or dynamic? Generally speaking a CR of 11:1 requires more than 87...but there are alot of variables. In the back of my mind I wonder if Polaris has it running on the edge to get that 70hp,so until I get more info I'll run higher octane fuel.

 

Good point HighOctane, I didn't take into consideration the compression ratio of the XP. With it being @ 11:1, it would be almost essential to put in premium so I will be doing just that.

 

I was told by my dealer that when he was talking with polaris engineers when they released the 850 that the original motor put out 90hp.They detuned it with a different intake for sure but they didnt say what else they did but i would bet on timing with the compression it has.Some one will probaly come out with some aftermarket goodies.

 

<div class="FTQUOTE"><begin quote>Originally posted by: sdbowcrazy

I was told by my dealer that when he was talking with polaris engineers when they released the 850 that the original motor put out 90hp.They detuned it with a different intake for sure but they didnt say what else they did but i would bet on timing with the compression it has.Some one will probaly come out with some aftermarket goodies.</end quote></div>

I figure they have to have the ignition timing set up with very little advance. A cam profile(long duration and alot of overlap) can be set up to bleed off some compression but that only really works at lower RPMs. I wouldn't be suprised at 90hp with that CR,with the right cam profile. Add some ignition timing advance and enough octane it should be a real beast! I question why they would do this? I mean it's great for us if that is the case but from a OEM standpoint it doesn't seem smart. Unless maybe they plan to keep the motor for awhile but continue to up the HP rating..but if they do that they have to start requiring premium fuel. Maybe for something like a Polaris version of the Renegade that might fly,but the average joe probably isn't going to run premium in his utility ATV right? I'm not average..I'll spend a little more per gallon for the power,lol.
Here's why I don't think that type of think is smart from an OEM standpoint.. Say someone gets a tuner and advances the timing but is not too bright and runs pump gas,they melt a piston or 2 put it back to stock and file a warranty claim.... basically the same scenario Ford ran into with the 2003/2004 Supercharged Mustang Cobra. They finally got smart to it,but not before spending alot on warranty claims. Then they knee jerked and it made legit warranty claims a hassle as they had special warranty adjuster inspect the vehicle.

 

I run mine on premium. It's about 10cents a liter more and the tank holds 20 liters so it only works out to $2.00 on a complete fill. Our premium is usually 91 or 92 octane so it lies right in the middle of too little or to much.
Take care,
Dave

 

91-92 is probably perfect. My first tank was 89, I wish I could get 91 as I think it would be ideal,but it isnt available around here. So in the future i'm going to mix 89 and 93 50/50. I just filled up with 93. Now I just need to find a good spark plug to run so i can get the Champions out of there. I prefer NGKs. Looks Polaris pulled another fast one, the REA6MC Champion isn't even listed in Chanpions catalog so I can't easily look up a cross.