I have a '99 Xplorer400 with about 1400 miles on it. Lately, its been acting up. Acting up as in it sputters and skips at mid- to high-RPMS. Its DEFINATELY not making the power that it used to. I believe my problem is an overly rich condition, but I'm not quite sure why, seeing as how I've never changed the jetting at all, nor done anything that would require a change of jetting. I have, however, fouled 4 plugs through normal riding (no excessive idling) just this season, so I know that something just isn't quite right.
I've tried cleaning the pre-filter, but that did next to nothing. The air filter has never been replaced, and I believe this is where my problem lies.
Can anyone give me some advice on this? I plan on purchasing a K&N filter right off here, so will an overly rich condition, combined with a new filter, create a more balanced fuel condition?

Change your air filter!!! Your poor bike is starving for air!! I clean my foam filter every 3 to 4 times I ride. I can almost gaurantee that is your proplem. It will also save you some plugs, and give you more power. 2 stoke engines need to breath a bit more than 4 strokes.

Okay, great. I'll pick up a K&N filter at the Polaris dealership tomorrow afternoon.
Thanks for the help!

Also, about how much is a K&N filter gonna set me back? 50$? 75$?

Polaris retail and what we sell them for is $29.99.

Does the K & N give more power?

I have a '99 Xplorer400 with about 1400 miles on it. Lately, its been acting up. Acting up as in it sputters and skips at mid- to high-RPMS.

..... I believe my problem is an overly rich condition I have fouled 4 plugs through normal riding

* Is there the odor or a rich condition or the smell of gas when somebody rides behind you?


The air filter has never been replaced, and I believe this is where my problem lies.

* Sure could be
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If after you change the air filter it still does misfires and runs rich it could be one of two things.

1. A worn inlet valve needle and seat will cause plug fouling, gasoline odors and a rich condition.

2. The electronic throttle control needs adjustment or replacement.

The ETC will cause the motor to cut out exactly like you are explaining. Perhaps you have a combination of these two factors.

But definitely change that air filter first. Good luck

Victory, the smell of 2-stroke exhaust is a bit stronger than I remember it being, but it doesn't smell any different, and I've not noticed the smell of gasoline, so I don't think the valve inlet needle and seat could be to blame.

My local Polaris dealer gets K&N filters on mondays, so I'm gonna swing by and grab one on the 18th, I'll give you a report then on how its doing.

As for the ETC, I don't think its this, because the power it makes changes with the temperature, as an engine normally does. The other day was rather cold, and it ran better and would rev higher, but today its in the 80's and isn't making as much power, nor will it rev as high. I believe that if it were the ETC, it would cut out at an unchanging RPM-level, and not fluctuate with air temperature/density.


And weedy, the K&N filter is supposed to allow for up to 50% more airflow than a stock paper filter, which translates into more power. I think if you ask anyone that has one, they'll say that it improves power a noticeable amount. I'd say that I could tell you what power gains I notice upon installation, but its going to be positive no matter what. I have almost no where to go but up, so I can't really say that my account will be very accurate.

Have you played with you air screw adjustment? This could also be a factor. Have you ever played U-Boat commander with your quad? Sinking or drowning out your machine sometimes will get dirt in your choke cable circut creating the same problem.

Go one jet larger with your K&N. I ran a 220 in my 99 Explorer when the temp where below 60 degrees. 80 degrees and warmer you could run a 210. Just make sure you check your plugs after running.

Odin, I messed with my air mixture screw in the spring, when the temperature rose, in an attempt to lean it out a bit. And, that was during that hot week in the spring when it was in the 70's, and it ran fine then, so its not that.

The deepest mud I've had it in was just above the left floorboard (lower on the other side)... is that deep enough to get into the choke cable circut?

The average summer temperature up here in Maine is usually between 70 and 90... is there any way I could adjust the clip height with either the 210 or the 220 so that I could stay right in that temperature area?
Or could I just use my air screw and make it richer on cooler days, leaner on warmer days, and still keep the stock 210 main jet?

Not too long ago, I had the same problem with my Magnum. I played around with it for a while and found that when I took the air filter off, it would run fine. So I got a new filter, problem solved. Just the other day, I washed the quad and took it to the shop, after I got it back, it started again. I called the dealer and he said to take the slack out of the throttle box as that is the problem with a lot of these. I did that and didn't fix it. I took the airfilter off and it fixed it. I called back and asked if that could be it, he said If I had gotten the filter wet when I washed it, then It would close the pores in the paper and not let enough air through. So I said enough of that, I ordered a unifilter that should be in tomorrow.