03 RMk wont hold RPM

[theultrarider]

If it was me I'd spend a little more time and get the jetting set spot on. I ended up dropping my jetting down 5 jet sizes last year to get the perfect color on my plugs. And it changed the RPM's big time and then I dial in the last couple R's with the weights dropping to a 10-56 and may go lower yet.
Get some good info on plugs there's more to it than just looking for Brown on the plug. It took me some time but I have it perfect now.

I think you are way fat on your 390's. I am running 360's at 1-3000 ft with slp race twins and am still fat. I think I should be down around 330's. Get your jetting dialed in first, then the clutching.

 

[winter brew]

I think you are way fat on your 390's. I am running 360's at 1-3000 ft with slp race twins and am still fat. I think I should be down around 330's. Get your jetting dialed in first, then the clutching.

I agree...jetting is fat, try 360's, needle in the middle, should still be plenty safe. I would keep your clutching the same, bring some 10-60's or 10-62's.....should pull them once things are running strong.

 

[mad1818]

Take it to someone who knows what their doing or your going to end up burning your motor down.

 

[JohnnyH]

I agree...jetting is fat, try 360's, needle in the middle, should still be plenty safe. I would keep your clutching the same, bring some 10-60's or 10-62's.....should pull them once things are running strong.

I dropped down to 370's needle in the middle.
World of difference on the trail.
On the hill with the new 3-4' of powder slowly gets loaded up and R's fall off fast.

Will check plugs and piston was tomorrow.

Will plan on some 350's maybe 340's for next week.

I think that I am heading in the right direction. . .

 

[theultrarider]

Good to hear! You are defintely headed the right direction. Just start paying attention to your plugs and wash now. You'll get it cleaned up and then hang on for the ride lol.

 

[IceCap]

Sounds like your running fat, However you mentioned that it hits 8800 rpm then drops off.......tells me that you have secondary problems not shifting out properly then not backshifting under load.

 

[theultrarider]

I just reread your first post and at 7-11000 you are still way fat. Did you try a different secodary spring or just the jetting? Lean it out quite abit more and try the black/purple spring. It should start coming alive for you. Someone gave you his set up for an 02 at your elebvation, bear in mind the 02's must run BIGGER jets than the 03-05's so with his 290's you should still be rich! I believe it since a m running 330's at 1000-3000. Don't be afraid to go leaner, just make sure to read your wash when doing it so you don't learn an expensive lesson.

 

[JohnnyH]

I just reread your first post and at 7-11000 you are still way fat. Did you try a different secodary spring or just the jetting? Lean it out quite abit more and try the black/purple spring. It should start coming alive for you. Someone gave you his set up for an 02 at your elebvation, bear in mind the 02's must run BIGGER jets than the 03-05's so with his 290's you should still be rich! I believe it since a m running 330's at 1000-3000. Don't be afraid to go leaner, just make sure to read your wash when doing it so you don't learn an expensive lesson.

I did not change anything in the clutches, I ordered a blk/ppl (160-240) and a blk/white (160-260).

I wanted to only make changes to one system at a time so I know what changes do what.

How does the saying go. . . . . . . "if in doubt lean it out"

 

[mountainhorse]

ttt

 

[JohnnyH]

So after messing around all last year with different clutch setups and jetting I worked all the way down to 280 (Yeah not a typo 280's) mains before my plugs started to lighten up and the EGT's to get hot. I checked the choke cable and it is not adjuted too tight or sticking. The sled still runs like a 500 jetted way too rich in the powder but on hardpack runs hard and fast.

I checked the compression-160ish +or- 3 psi
TPS is 4.1V @ WOT
The timing was 2* or 3* off (retarded)

I bumped up the timing to 32*-33* (Spec is 29*)

I dont want an other year of the sled running like Poo

Ideas. . . .

 

[Mtn Escape]

When your sled starts to bog, is your hood covered in snow? My 03 Escape, when I was in deep powder, hood covered in snow it would bog like it was jetted fat. Found around the head light the foam seal had pulled away and was letting snow and being sucked into the carbs.

I would look there. For a whole year I spent messing with jetting trying stop the bog and found that.

 

[JohnnyH]

When your sled starts to bog, is your hood covered in snow? My 03 Escape, when I was in deep powder, hood covered in snow it would bog like it was jetted fat. Found around the head light the foam seal had pulled away and was letting snow and being sucked into the carbs.

I would look there. For a whole year I spent messing with jetting trying stop the bog and found that.

It will do it with no snow on any of my vents, and does not matter if the right side (exhaust exit) is totally out of the snow either.

The headlight has been resealed.

 

[JohnnyH]

Ttt

 

[RottenScummyTroll]

Just throwing this out there, but have you checked your exhaust valve diaphragms?

I had a similar problem where it would lose RPMs on the trail after initially taching up fine, and it turned out I had a ripped diaphragm that was allowing one of my exhaust valves to creep closed. Worth checking.

 

[JohnnyH]

Thanks, both exhaust valves, springs and diaphragms are A OK.

What could be going on that I could run 280's and not burn down ???

 

[whoisthatguy]

Those main jet sizes, scare the hell out of me. They are not even close. I love the smell of burned up pistons in the morning. About a mile out of the snowpark. 1 to 3000 feet should be about 450's at 20F to 35F. The engine will starve itself of gas if the suction hose gets hot from a hot engine that is being wound out. The hose softens up and cuts off the suction at the hose bends. Particularly the new and improved Red Hose from Polaris. If your polaris dealer sold you the O-rings that are not high temp like mine did, you will start sucking coolant into the pistons and burn up everything as well. He had to do a lot of begging to get those outdated O-rings from Polaris, just so he could screw up my sled.

 

[shortstop20]

I think you are way fat on your 390's. I am running 360's at 1-3000 ft with slp race twins and am still fat. I think I should be down around 330's. Get your jetting dialed in first, then the clutching.

How in the heck are you running 360's at 1000 ft? That is NINE sizes lower than stock for that elevation and that's on a stock sled.

 

[JohnnyH]

Those main jet sizes, scare the hell out of me. They are not even close. I love the smell of burned up pistons in the morning. About a mile out of the snowpark. 1 to 3000 feet should be about 450's at 20F to 35F. The engine will starve itself of gas if the suction hose gets hot from a hot engine that is being wound out. The hose softens up and cuts off the suction at the hose bends. Particularly the new and improved Red Hose from Polaris. If your polaris dealer sold you the O-rings that are not high temp like mine did, you will start sucking coolant into the pistons and burn up everything as well. He had to do a lot of begging to get those outdated O-rings from Polaris, just so he could screw up my sled.

So. . . . I think that you are saying that the fuel lines to the fuel pump and from the pump to the carbs will restrict flow to the carbs and lean out the motor and sieze

Are you talking about the cylinder head o-rings
I dont have a coolant problem

 

[whoisthatguy]

The problem with the fuel pump for some years is caused by the bends and ensuing kinks in the SUCTION HOSE ONLY, that attaches to the bottom rear of the crankcase. The fuel pump stops working and shuts the engine down so fast that it doesn't have time to burn the pistons up. The original stock black rubber hose with a fiber cross weave, has a far less tendancy to kink when it gets warm. The Polaris update that was sold to me was a red plastic hose. Of course, the dealer may have deliberately sold me the wrong hose for that as well.

The hi temperature o-rings that I was referring to, sit on top of the cylinders and below the cylinder head.

Defective hi-low beam switches also cause RPM problems, believe it or not. Defective CDI boxes will also cause RPM problems. I have a new one for sale that is guaranteed to be fully functional, for $50. Polaris will gouge you about $340 for the same item. Never hurts you to carry an extra around for an old sled.

Thermistor wires may be wearing out. Some Polaris dealers like to bend the wires over as they come out of the top of the thermister, in order to sabotage the sled and cause premature engine failure. Which may then kill you when you break down 30 miles from your ride home, in a snow storm.

A stator that is going out may miss now and then and may have trouble idling at the same RPM's.

 

[JohnnyH]

The problem with the fuel pump for some years is caused by the bends and ensuing kinks in the SUCTION HOSE ONLY, that attaches to the bottom rear of the crankcase. The fuel pump stops working and shuts the engine down so fast that it doesn't have time to burn the pistons up. The original stock black rubber hose with a fiber cross weave, has a far less tendancy to kink when it gets warm. The Polaris update that was sold to me was a red plastic hose. Of course, the dealer may have deliberately sold me the wrong hose for that as well.

The hi temperature o-rings that I was referring to, sit on top of the cylinders and below the cylinder head.

Defective hi-low beam switches also cause RPM problems, believe it or not. Defective CDI boxes will also cause RPM problems. I have a new one for sale that is guaranteed to be fully functional, for $50. Polaris will gouge you about $340 for the same item. Never hurts you to carry an extra around for an old sled.

Thermistor wires may be wearing out. Some Polaris dealers like to bend the wires over as they come out of the top of the thermister, in order to sabotage the sled and cause premature engine failure. Which may then kill you when you break down 30 miles from your ride home, in a snow storm.

A stator that is going out may miss now and then and may have trouble idling at the same RPM's.

The CDI,Stator and ignition coil had crossed my mind but I dont want to start throwing parts (I might have to) at it on a WAG.

Where are these thermistor wires located and what is their purpose ???