2001 Polaris 440XCF Jetting

**crush4size** · 02-14-2009, 08:02 AM

Sled: 2001 Polaris XCF 440
Fan cool Fuji - VM34 mikuni carbs - Runs great at idle, engine acceleration is smooth to 4700 at which point the clutch engages, the engine RPM's drop 2 - 3 hundred and the sled starts to move. Very normal 1/4 throttle performance. At 1/4 throttle the sled goes 10 -12 MPH, engine RPM's are 5000 +/-200. The clutch doesn't shift out unless I'm on hardpack.
The problem is getting the engine to spin past that 5500 - 5700 RPM point. When the engine is cold (not at operating temp) its fine. One lap around the farm, and you have to feather the throttle to get it into the power band.
I bought this sled 6 weeks ago, after purchase I started with stock jetting as my baseline.
I have put in #40 pilots (#45's are stock) and gone from 340 (PTO side) and 330 (MAG side) to 320 and 310 respectively. Little change in throttle response. One common in the changing of the main jets that is quite noteworthy, every change in main jet size, I start with the jet needle clip in the center...every time I have to set the clip in the highest position, or it is horribly unresponsive. That is where the clip was when I purchased the sled. Anyone out there has experience with this model year XCF - and resolved this issue??

**spike** · 02-14-2009, 08:48 AM

My brother had a 01 Pro X 440 fan race sled, I have tried everything on that sled. Sometimes you could barely get it to roll across a road crossing when warm. The best, most trusted Polaris tech i know told me it's the nature of the beast with that sled, it's in the timing or something. I hope we are talking different sleds because i have never heard of a fix. (Rumors of the clutch/belt getting hot are not the issue either.) This was a great riding sled though, i hope you get it figured out, i'd be real interested to know.

**2doo** · 02-14-2009, 12:17 PM

I know nothing about the sled in question, but if you're peddling the flipper to get it to pull enough fuel to go, sounds like jetting is too lean on the pilot, and/or have you done a compression check?

**crush4size** · 02-15-2009, 05:34 AM

I'd be willing to bet, the mills in the Pro-X fan and XCF are the same. I can't find the Pro-X fan listed as a production model, so I cant research the engine.

I read a thread on a different site (I cant find the thread again) that recommended a leaner needle jet. The stock is a Q-2, replacing it with a Q-0. My understanding is that will make it leaner throughout the effect of the jet needle.

I did a compression check before i bought it, they were 125 and 120 psi.

If the engine were starving for fuel, I would expect flipping the choke would help the engine hop that range of RPM's that it would normally stumble over.

I am researching needle jets; the stock ones are stamped 286 Q-2. I can’t find any type 286 jets.
I have some old VM38's, I pull a needle jets on one and it is stamped 480 Q-0. I can find 480 type jets; they are listed parenthetically as 166. The VM34's are listed as 159 type jets.
I am very puzzled.

**cooter92** · 02-16-2009, 04:47 PM

I have the exact same sled with what sound like the exact same problem.I have rejetted all the way down to 300/290 and changed the pilot as well. I have checked the compression which is fine and so are the crank seals. I have changed out the primary and secondary clutches just to make sure. I am wondering if the CDI is bad. If you find a cure please let me know and I will do the same.

**m_scott** · 02-20-2009, 08:18 AM

Originally Posted by crush4size

The problem is getting the engine to spin past that 5500 - 5700 RPM point. When the engine is cold (not at operating temp) its fine.

only thing that comes to my head is let it warm up. I know my sled wont go above 5k till warm. Like Al said it sounds like a dieing lawnmower. For some reason my temp light stays on when cold till it warms. Once the light goes off the timing is adjusted and its back to 100%

**ctbcam** · 03-03-2009, 05:37 AM

if you encounter a rich running 2001 440 xcf, replace the stock Q-2 needle jet with a Q-0 (286 series) and change the main jetting to 0-3000ft (+10-+40degress) pto330-mag320 needle jet middle position. then change the multi angle helex to a 34degree helex put spring in #3 hole and that sled will rock!! my son was very happy with this change. I have a sightly used 34degree helex for sale it has 2 miles on it. pm me if interested.

**crush4size** · 03-04-2009, 02:05 PM

Sorry if I appear simple, but I cannot find ANY info on Mikuni 286 series needle jets. Where did you find them?

**ctbcam** · 03-04-2009, 06:42 PM

have your polaris dealer run the vin# and print you a copy of the service update or give me a fax# an i will give you a copy of mine.

**HellBender** · 03-07-2009, 05:08 AM

I too am looking for a Q0/286 needle for a 1999 440 H.P.fan with the same symptoms you all have. I have had successful results by using smaller pilots jets if this would help anyone. Here's my story.

I have two 1999 440 fans. One is a XCF which runs great
(#40pilots,6DP1-3 needle into P8/420 needle jet with 230 mains).

The other is a XCF-SP which loaded up with gas at 1/4 throttle. I crossed my fingers every time the clutch engaged & never stopped on a hill.
(stock#35pilots,6DH7-3 needle into Q2/286 needle jet with 330/340mains).

I'm told these power plants are ported different even though they look the same. These carbs are jetted different and I tried to match the jetting but that made no difference to the SP. With the exception of dropping the 6DP1 needle into the Q2/286 needle jet with #25 pilots but the upper throttle was flat. It was only a slight improvement until I opened up the air screw then she would scream. But then you needed to use the choke to keep it running at idle.

The P8/420 needle jet ran just as fat as Q2/286 did and a Q0/159 was way to lean.

My best experience to date is slowly working the Pilots down. I'm currently running with #20 pilots, air screw 1/4 turn, 6DH7-(top clip), Q2/286 needle jet with 320/330mains. I ran it hard around the yard for 15 minutes in 40 deg weather. Then we trail rode 70 miles in 25-35 deg weather. We even got stuck behind 4 groomers and 30 sleds with a lot of stop and go, on a hill no less. Runs good enough to ride but still gasy at lower throttle.

My plan is to try the Q0/286 jets using the 6DH7 needles. Match them with small pilots. Then carry a pair of 6DP1 needles for insurance.