Help with odd running sled

[chriswelters]

Hey guys, on vacation in Wyoming and I have an odd running snowmobile.

Its a 2013 pro rmk 155. Had the sled out here last year and everything is the same. Mds weights, black green primary spring, and stock sec spring. GGB can.

The snowmobile runs at 8400rpm on a packed trail at 6000-7000ft. When under load in powder if its hamming on it on the flats or driving up a hill it drops to 7500-7900.

The snowmobile was at a polaris dealer. The clutches were completely gone through and everything is fine. Hooked it up on the computer and it showed max det both cylinders 2 different times only. Made many bogged pulls up hills all day.

The dealer thinks it is bad gas. Anyone with ideas please chime in.

 

[jdw1]

What elevation are you riding at?

 

[canj]

It's so easy for the dealer to blame the gas...

 

[xc6rider]

Definitely start with fresh fuel, spark plugs. If it's a consistent issue, and the only codes you're getting is det, I also would lean heavily towards a fuel issue.
Bad fuel, plugged filter, or pump...

 

[chriswelters]

Elevation is 6000-7000ft ^

 

[jdw1]

Is it set to run on ethanol or non-ethanol?

I would also check for broken primary spring, I had a broken spring but I had to disassemble clutch to see it so you might have to remove the cover if you feel comfortable doing so.

 

[chriswelters]

It is set on the ethanol setting. The clutches were completely taken apart by a dealer with me watching.

 

[jdw1]

It is set on the ethanol setting. The clutches were completely taken apart by a dealer with me watching.

Have the clutches been taken apart since the dealer looked at them?
My point is the spring might have broke after they put them back together!
The other thing that may have happened is that maybe the dealer/mechanic dropped a washer from the back of the secondary and now the clutches are mis alined, Im just trying to think of what might have happened. Did you ride the sled at home, and did it run good then?

Where are you in Wyoming?

 

[chriswelters]

They have not been taken apart since yesterday when they took them apart, sorry.
The mechanic took a spacer from the shaft of the sec and said it needed a little more float.
The sled ran great at 0-2000ft in the U.P. all I did was adjusted thr MDS weights for high elevation. Ran great one day in the U.P. then the next week right away in jackson its as stated above. I did not ride it inbetween and didn't do anything else. Just hard to believe its the weights.

We are in jackson Wyoming

 

[jdw1]

Sorry I misunderstood when the clutches were taken apart.

Well I just found my bog but it sounds different than yours, mine was at WOT but not when I would accelerate moderately, If I hammered on it it would bog and not come out of it until about 6500, mine was the EV exhaust valve solenoid, so if you are riding with someone with a similar sled swap out the solenoid, if you do this just swap out the solenoid and all the hoses that way you don't risk the chance of breaking the plastic fittings on the solenoid, hopefully this makes sense.
One thing I learned with mine is if it is not setting off a code it's more than likely something mechanical, I had to do a process of elimination on mine. Have you done a compression check? How about a fuel pressure check?
I though mine was a fuel issue but not.

 

[jdw1]

One other thing, some sleds had issues with the throttle safety switch, you can't bypass it ether because of a resistor in the switch.

 

[Laramie]

I'd agree with JDW1. Check your exhaust valve hoses, fittings and silenoid. Do you have any black oil residue on your engine that wasn't there before? If you do it's a good indication something's going on with valves loosing vacuum.
Also 8400? On max RPM is a little high. 8150 on a hard pull is what we shoot for and 8250 on groomed trail.

 

[jdw1]

Well, are we up and running or what?

 

[chriswelters]

We didn't get much riding in yesterday but at the end of thr day it opened back up and was running 8100-8150 in deep wet snow. I think I put on around 20 miles. Drained the gas and put new in.

 

[fastlane]

Whats the coolant temp doing? My 13 had same issues, i could pull a hill be 8200 all the way turn around same hill and 7600, looked at my temp and it was 150 on the 7600 pull, let it cool down bang back to 82, sold it that machine but I did the trs t-stat mod on my 14 and it runs way cooler than my 13 did, like 105 boondocking, 110 hardpack with scratchers down, same hardpack with scatchers up 118 ish.

 

[chriswelters]

My temp is in check. Usually 120-125 in the pow. Sled ran better today. Deep powder today and it ran 8000rpm on a hard pull. Sometimes 8100

 

[chriswelters]

Just a quick update on the sled while heading home from Jackson. Sled ran better after I siphoned the old fuel out and ran it a whole day.

I still was not getting my top rpm I wad after which was around 8200. I decided to bite the bullet and get some stock 10-60 weights. Let me tell you what, that was the ticket. Ran amazing after that in all types of snow.

The MDS weights I was running had the drilled out bolt in the tip of the weights. No washers and no other bolts and was only getting 7900-7950. Not sure what the problem was since I ran it all last year with no problem.

On a side note I am getting rid of my GGB mountain can because its to loud for my taste.

 

[lucasMX358]

If your having problems with the mds, i would suggest the rooster adjustables. I have the rkt drop in and head with boondocker box in my 13. Complete different sled, i pull 8400 all day long. Rooster weights are spot in, load heavy as possible in the heel, little in belly nothing in the tip. I also running the ggb and agree its a little loud. Good lick on sled

 

[mtncat1]

I'd agree with JDW1. Check your exhaust valve hoses, fittings and silenoid. Do you have any black oil residue on your engine that wasn't there before? If you do it's a good indication something's going on with valves loosing vacuum.
Also 8400? On max RPM is a little high. 8150 on a hard pull is what we shoot for and 8250 on groomed trail.

I've been having a problem pulling peak rpm lately and am concerned about my pv operation. can you explain a little more why the oil in the bellypan would indicate a ev solenoid problem. thanks

 

[04proxr800]

I'd also like to know what the oily residue has to do with the power valves!