Finally got to take my 04 viper mountain out last year for the first time on an ice fishing trip last year. Ran into some trouble though, which I was quite surprised about because the sled is really in great shape. Got to the spot we wanted to fish the first day and it started to over heat. There was about 5” of hard packed snow on the lake, but nobody else was really having trouble with it. I road it as little as possible throughout the day but when I did the DCS light came on. Finally at the end of the day the light came on quite a bit and eventually it blew up. Did a compression test and the cylinder farthest from the belt side was around 82 psi. My plan is to tear into it within the next few days, but I need to figure what caused it. What should I look for? Or was it just not enough snow. Most of the other sleds were long tracks and they didn’t have any issues with it.
Is it stock and was the jetting ever changed? Are the carbs cleaned good every year?
If it was running well, I might venture to guess crappy fuel, coupled with no loose snow for cooling.
Seemed like it was running fine that day. Gonna drain the fuel and check the jetting. Did go from Colorado to Maine. Got it torn apart this is what it’s looking like.
I would guess its going to be really lean if it was never changed when it went down in elevation. Should be at 156.3 mains, #45 pilots, 3rd clip, 1 7/8 fuel screws.
That is definately a heat seizure.
I agree the jetting should be checked to ensure it is set up for low elevation.
Check your oil pump cable adjustment and don't be afraid to run the oil pump on the richer side[less cable slack]
You should try to pick up an opticool head gasket for the Viper engine, maybe Hauck still has them.
The sled should have a rear heat exchanger, if it doesn't install one.
Be very fussy about bleeding the cooling system when you reassemble it...they can be troublesome to get all the air out of the system.
A good set of ice scratchers will help keep the engine cool in icy conditions.
I agree the jetting should be checked to ensure it is set up for low elevation.
Check your oil pump cable adjustment and don't be afraid to run the oil pump on the richer side[less cable slack]
You should try to pick up an opticool head gasket for the Viper engine, maybe Hauck still has them.
The sled should have a rear heat exchanger, if it doesn't install one.
Be very fussy about bleeding the cooling system when you reassemble it...they can be troublesome to get all the air out of the system.
A good set of ice scratchers will help keep the engine cool in icy conditions.
Good to know thank you. I’m gonna look into all of that today. What do you guys think of this? Anything I should worry about?
You should verify the carb jetting and the clutching/gearing to make sure you are set up for the conditions you are riding at. Big differences in an 8000’ Colorado set up vs a flatland setup.
Main jets were super lean pulled out 140s. As for the pilot screw it seemed to be turned out a bunch, if I’m correct the seated position is turned all the way in right? Then turn it out 1 7/8 turns correct? Now for the jet needle adjustment I pulled the top cover off the carb but don’t see any clip to adjust like in my manual. 
To get at the needles you have to release the throttle slide arms form the throttle shaft and the slides, you then swing them up out of the way to expose the tops of the needles.
Alright thank you! Am I correct about the pilot screw?
Yes on the pilots. Count the turns out from lightly seated.
Thanks! That’s what i thought except they were turned out 5 or 6 turns.
you need a 2.5mm ballend allen wrench to get the 2 little screws that hold the slide to the linkage after you take off top. open the throttle a little and the arms will move out of the way to get the screws.