horkn,
Here's a quote from SnoWest magazine concerning the 800 CFI setup.
The injectors in the crankcase deliver fuel at idle and high rpm while the injectors in the transfer ports deliver fuel at low and mid engine speeds.
If you read ride reports of preseason machines you will see that nobody complains of a bog anywhere within the throttle range, most of them just say this is the fastest and hardest pulling stock 800 they've ever ridden. Now at production time we have many people(mostly at low elevation) that are experiencing a bog on their machines.
Most of the 600 CFI 4 and 700 CFI 4 machines seem to be running well after the latest reflash.
I have heard of a few CFI 2's that have the bog as well. I agree the CFI 2 is a better setup and ride reports confirm that but if they don't leave the factory correct it's a mute point.
Polaris introduced the 800 CFI in '08 for RMK models only so a vast majority of their fuel mapping testing was done at high elevation I'm sure. I remember hearing reports of flatlanders riding their '08 Dragon RMK 800's at low elevation and having the same problem guys are this year with their '09 models at low elevation. Think about carbed snowmobiles for a moment, many of them(all Polaris sleds for that matter) need the needle adjusted when switching from high to low elevation(along with the mains of course). Now think about the CFI system going from high to low elevation, if they don't "fatten" it up enough it will be lean in the midrange, which it is. Many have reported A/F ratios of 15 or 16 to 1. Compared to WOT where the ratio is 10 or 11 to 1 if I remember correctly. Polaris didn't do enough testing at low elevation to keep the midrange from running lean and the strict EPA regulations do not help any. Then there's the fact that they are pig rich at WOT(at low elevation at least). Both of these things have been verified by many people by checking plugs, wash, air/fuel ratio sensors, and EGT's. ......but then there's some people riding their RMK's and short tracks at low elevation without any bogging issues of any sort. All of these things lead me to believe that they are not all leaving the factory the same(TPS mainly) and that Polaris has not done enough testing at low elevation with these sleds to get a good fuel map for them. Most of the RMK's seem to run great at high elevation but considering the fact that they can run less octane at high elevation with the ethanol wires connected(for premium fuel) and that Polaris has done extensive testing on the fuel mapping at high elevation it's no surprise they run good there.
I have rode a '08 Dragon RMK and it had the bog whether you chopped the throttle open or went into it steady, didn't matter.
I have my doubts about the Iridium plugs but I guess it's worth a shot.
At worst, the aftermarket will fix it, with a cheaper resolution than getting a power commander or similar box. I bet if all users that have an issue try the iridium plugs that the numbers of complaints of the bog will go down.
Do you mean a reflash of the ECU? I guess that's an option but I don't see that happening, at least not for low elevation riders. I would much rather have a PCIII and tune it myself than wait for Polaris to fix it but I can understand that some don't like to tune sleds. Many people have been using the PCIII boxes along with watching plugs, wash, air/fuel ratio and EGT's as I said before and have completely cured any bog, surging, poor MPG and poor performance.
I am convinced that incorrect TPS settings have caused most of the issues as one dealer I spoke with stated that 29 out of 30 800 CFI's they tested had the TPS set incorrectly.
The fuel quality today doesn't help any(4 strokes have a definite advantage there). Almost all reports show that these sleds run 10x better with non-oxygenated 91 octane fuel with the ethanol wires plugged in as compared to 87-91 octane WITH ethanol and the ethanol wires disconnected.
Polaris sleds haven't been fast out of the box for several years, if they would start making them fast stock they would sell many more sleds, maybe even taking back #1.
VenomMod,
Your friends may be experiencing some icing between the outside and the center extrovert driver. It happened to a few people last year but was pretty isolated. They could try spraying some Pam cooking spray on the side of the drivers(not where they drive the track), in order to keep the ice from building up. That's an old mountain rider trick to keep ice buildup at a minimum, they used to do it to tunnels. That Assault must have a leaky chaincase seal or something because having to refill the chaincase oil already is ridiculous, let alone 4 times. Is the fluid milky at all? Tell him to check the seal on the inside of the chaincase. Reach up into the tunnel and put your finger where the driveshaft and bearing meet. If it's wet there the seal is junk.
..with nothing better to do.
