2004 Vertical Escape Carb Icing?

04' Vertical Escape, carls ported, SLP twins, bored carbs, SLP cold air intake, Jetted at 310 PTO, 320 MAG. Altitude 8,000' to 11,500'. Added 2" intakes and one 5" intake screens from SLP into the dash area. Still have speedometer and tach in place. Running a NGK replacement spark plug that was sold to me by Steamboat Powersports as they don't carry Champion for some reason. First time using these plugs but sled has done this with the champion plugs too.

I clean the intakes off every chance I get since they always collect snow on them, I'll even clean them while moving if I can. I don't feel like I have an airflow issue at this time.

In deep 2'+ loose snow I have an issue with it cutting out and becoming basically unridable. Really bad in the mid range, sort of ok on the top end. Let it sit for five or more minutes and it will run really well throughout the range for a short while, maybe 4-5 minutes in deep snow. I was running a 320 PTO, 340 Mag and jetted down to the above in an effort to get it to lean out thinking that was the issue. This sort of worked but not entirely.

When I changed jets the sled had been sitting for several minutes and the carbs were really cold and had ice on the bowels. Nothing that I could tell inside of them but they were certainly icy on the outside. My cold air intake was barely hanging on so I took it off which should allow for some under hood heat to get pulled into the engine. This again helped a bit and made the top end pretty good but the mid range sucked and was not really usable.

One last thing is that I have an avenger III for EGT's and water temp, Been riding this sled long enough to know that even on the lean side with this jetting I was ok with it at 11,000. But my water temps were down in the 90 degree range and sometimes colder, on a several minute rip uphill at full throttle I would see water temp creep to 100 degrees.

I have a new thermostat ordered already to see if I can get some engine heat built up again, but could I be icing the carbs and causing most of my issues?

I didn't have the hood vents blocked which was allowing some snow to hit the pipes and cool them off which could be a contributing factor. However I was riding around with snow gathered on the hood for a long time so I can't imagine that it just kept pushing snow through the screens and cooling the pipe off. I think the snow buildup made a temporary barrier from more snow getting to the pipes.

Thoughts?

If I'm icing the carbs what can I do to stop that from happening?

I looking for a good used SLP single too as I'm kind of done with the finicky twin pipes and want more daily rider type reliability.

sled_guy said:

It's a twin pipe issue. I have run these motors since 02. Every single one I have ever seen with SLP twins has the same issue. You can fix it, but it takes effort. Venting the crap out of the hood helps, but then you run the risk of dumping snow on those twins, causing steam under the hood and then it kills the motor.

Here is what I did to fix the issue finally on my 910 (which is just a big bore 800).

1 - Pulled the speedo and put a flowrite in its place along with all the other ones you have already done.
2 - Made sure the air box was sealed to the carbs good and to the under side of the hood so that it pulls cold, fresh air only.
3 - Added venting along the right side of the hood to allow the pipes on the chain case side to cool better.
4 - Put metal screens in the hood to keep snow from dumping in on the pipes.
5 - Sealed the exhaust outlet to the bellypan with black high temp sealer.
6 - Bought a Cat 900 exhaust deflector and put it on the bellypan, replacing the Polaris one. It is a cup looking thing that does a better job of deflecting snow. I have seen several guys move the exhaust outlet on their can in to the sock tower and that works even better. Note, this seemed to make the biggest difference for me, my theory is that the deep powder was restricting the outlet causing the motor to load up.

Or, you can just put the SLP single on it and go ride and never worry about it. That's what I did with my 800s. Unfortunately the 910 requires the twins.

sled_guy

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BILTIT said:

What about sealing up the bottom edge of the headlight to hood, snow gets in and goes directly to the intake. I never had any issues with my twins in my edge chassis' (both 03 rmk and 04 pro-xr have them), i also ran a holtzman atacc which reduces the finickyness of the twins.

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Thanks Guys,

That's sort of what I figured, twins are finicky anyways then add a little bit of snow turning to water, snow hitting the pipes in the front cooling them off, and needing one more flowrite (couldn't think of that name yesterday) and it's just too many little things making a bigger problem

Long ago I was headed in the 910 direction, hence to bored carbs, and twins. The ported 800 was simply a hold over for a year or two, then I had a kid, built a house lost my *** in the recession, had another kid and now a 910 is a thing of the past.

I want to get this back to stupid reliable so that I can use it as a loaner sled and get myself into a newer one in the next year or so. The single pipe just fits that model too well.

Found a pipe and getting money shipped out for it so that part is taken care of.

sno*jet said:

nobody will agree, but i would try some k&n style cone filters instead of the airbox. not the foam ones but the pleated type that are meant to flow even when wet. PSI used to sell some good ones. try it if you dont have any luck with the other stuff.
i also never run the fancy helix angles the aftermarket companies tell you to. great on the trail, wont pull it when the powders over the hood. I actually took the team off and ran the stock button secondary in those conditions.

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I thought about that since while we were out it seemed to run a little better when I pulled the cone off the hood. I don't know what under hood temps in a snowmobile are and that's probably highly variable depending on hood vents etc. but I could see simple cone filters helping keep some heat in the carbs.

I'm going the route of putting a single on and tuning that in. I don't have the riding time or budget to keep trying things. Plus these types of riding days only happen once in a while and I don't want to be the guy working on his junk all day while everyone else makes tracks.

Thanks all, I feel like the jetting isn't my issue. I've owned the sled since new and have nearly 4,000 miles on the chassis. A lot of those miles with twins, and the same gauge and probe placement for my EGT's I haven't burned it down yet! I think I'm entering that point that it's getting close to being too lean but not totally on the edge yet at least at the upper levels.

I really think my issue is intake related with a bit of snow hitting the pipes to help the downward spiral. I messed around buying a single pipe so it's not here yet and another big snow day may be happening this weekend. I plan to get the intake sealed up, take a look at all openings into the gauge area and get them sealed since you can see the water sitting in the bottom of the air box and try to keep the snow off the pipes for now.

Since I want this sled to become a loaner spare type sled I want a simple pull and go sled that is well tuned with the least amount headaches when it's called into service. The single heads it in that direction and I'll buy a new Pro to ride.

Quick update:
Got another nice little blast of snow so I was able to try some small things out in 12" to 18" of powder with a soft base under that. Easy to get down a few feet in the snow and take some nice face shots in low spots.

I installed some weather stripping I had laying around between the headlight and the hood to try to cut down on that snow entry area, re-installed my SLP cold air intake, and put the new thermostat in.

Rode Yesterday and at low elevation it was good, even in looser snow. Then at mid level elevation for around here, 9,000' to 10,000+ feet it was terrible in the mid range again but just fine at full throttle, even left me sitting in a crappy place once cause it just wouldn't get out of it's own way. Let it sit and it ripped just like nothing was wrong. Water temps were up some but never much if at all over 100 degrees in powder.

At lunch I decided the only thing I could look at doing in the field that I hadn't touched was the needles in the carb. Pulled the tops and found that some idiot (ME) had the clip with washer under it sitting in the bottom notch so in effect full rich on the needles. Well I dropped them to the middle notch with the washer under them and low and behold the mid range was pretty usable. If I had more time I would have tried taking the washer out from under the Jesus clip and seeing if that little bit less gas made it better, instead of moving a full notch. A full notch leaner might be the answer too but some time looking at plugs and wash is needed at that point

SO in short I was jetted richer than I needed to be and somehow either messed up the needle position or was trying something and forgot I went full rich on the needles. I think with more tuning the twin pipes can be pretty reliable but don't fit what I want now, I will probably run them until I can make the time to install and tune the single pipe later this year. The side effect of leaning it down was that it runs more water temp now, probably because it's making more heat in combustion. One thing I forgot to mention is that I run straight AV gas. Not for octane but for a good clean fuel that stores easy and is easy for me to get here.

EDIT: Rode again this weekend in decent enough loose snow, I have added the flowrite in the Tach hole as well as put the SLP edge intakes down in the stock intake location, since I have a Vertical Escape I already had the socks over the regular foam but pulled that out when I put in the nice new aluminum ringed mesh SLP intakes. Stayed Jetted down with the needles in the middle position since I was riding at lower elevations. Overall the sled did really well, it had a few little hicups here and there but nothing that was too bad. So I think that I have it pretty solid with the twins at this point, I would have to ride in another totally epic blower powder day to confirm that, which I doubt will happen again this year for me. I should have my single pipe this week and will be going ahead and putting it on and tuning that setup in now. Just thought I would add more info for someone else later.