The infamous powder bog

Loneviper
That is what I normally run at that altitude, but with the head and can. So maybe my guess would be 145 if I add the vents??????
When I was stock I ran 140 at that altitude.
Do I make since?
OK
@4500-6000 Stock 145.........added can / head 147 or 148
@7500-? Stock 140.........added can / head 143 or 145
kinda depend on temps
So if I go with the vents maybe I should try
@4500-6000 148 (no less)
@7500-? 145( no less)
What da ya think?

You know you just may have hit on something, that this thread was all started for.
You said it would still bog if moisture formed on the air box foam!!!!!!
Here we go again with this moisture theory.....steam or fine snow dust entering the air box?????
I said earlier that I havn't experienced a major bog......I do run a pre-filter on my air box???? Maybe the cure all????
The mystery continues.
 

I had one dealer tell me 143.8 was pretty lean, another said fine. The only mod to mine was an SLP can so I left jetting as is. I would say with your heads ect you might want 145 or a little more to be safe aat our elevations.

My sled would run in powder all day but if it bogged at all, I would lift the hood and there would be a ton of steam and moisture on the foam. Mind you I had ALL the under hood air blocked off but that humid air would find a way to the foam and I think force the engine to go rich.

We should have a Montana / Wyoming connection some day if we ever get snow again.
 
Same story as lone viper with my SRX. The sled runs great until you get powder riding up over your hood. It's not the exhaust. I can tell you that (at least in my case it's not). Every time I got the bog, I would stop, open the hood and watch the pile of snow melting on top of my airbox. I think this may be the problem. If riding in the deep powder too long I would eventually foul plugs.
 
Since SNAKEBIT is taking no under hood air and has an air box pre-filter, I'm sure that a pre-filter is not the cure all.

I'm really leaning towards what SECA thinks it is, the cooling of one or more pipes from snow that makes it through the hood vents. I'm simply going to carry some tape with me, and experiment blocking stuff off when riding in powder. I'll start with under hood air, next try blocking hood vents one at a time (the reason for this is I think it is mainly the front, right vent from riders point of view, which is directly over a pipe), then use some electrical tape after that to seal off the plug caps (for a very short amount of time). If this doesn't solve it, then :dunno:

I'm pretty much done speculating until I can ride and experiment with some of these ideas. THANK YOU for all the input.
 
Mod-it, you misunderstood my post. I never bog. I raised the front and back of my hood 1/4" for better air flow. Have never turned on my carb heaters. Have filtered vents behind my windshield. Made sure my airbox is properly sealed to the hood. I have ceramic triple pipes that hold the heat better than panted do. I have not put any filters on the hood vents themselves. Some of my riding every year includes miles of riding with snow to the head lights. Other than ceramic coating to keep the pipes warmer I have no real good explanation of why I do not bog.
 
A K MntViper, I didn't misunderstand your post. I was talking about the fact that you don't bog, but your friend with the painted pipes does. To me this could be because your coated pipes are insulated better and thus don't allow them to possibly get cooled when snow comes through the vent and lands on the pipe. Your friends does because of the thin layer of poor insulating paint. If a pipe gets cooled, it can create a bog. I think the front right vent is the one that lets the most snow in and it is also right over a pipe, which makes sense on your friends sled. He carves right, the vent drops down into the snow, and snow lands on his pipe and cools it.

It sounds like your sled is set up just like mine, minus coated pipes and raising the hood up a quarter inch. This seems to re-enforce my theory of a pipe getting cooled by snow coming through the vent and landing on the pipe.
 
If you fix your problem let me know and if my buddy fixes his, I'll do the same. I'm working on solve the problem I'll let you know. We are doing one fix at a time to try and find the one or two that work best.
 
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Ok guys I was out riding today!!!! In the last three days we have recieved 30 inches of snow!!!! My Srx does have a powder bog that acures when I am riding or stop in snow that covers the exhuast port. I have not installed a deflector yet. I stoped with snow that was not over the hood and was not coming into my vents. when I went to push the go lever I was only able to reach 7000 rpm with the lever to the bar. As soon as I was out of the deep stuff the bog cleared!!!! Now I also was testing the exhaust cool down theory. I do believe that there is a issue with cooling down your pipes on tripple piped motors....when I allow my pipes to be covered with snow I also recieve a bog that will not allow my rpms to reach optimum levels. After taping my vents with duct tape I noticed that I was able to go into snow that was over the vents until it reach above the vents I have covered into the vents that I don't have covered. So this too is an issue. I don't doubt that injesting moisture into the air box is another issue, although I rode in snow that was coming down at an inch and hour and never, I repeat never had a bog issue until I either got my belly pan in too much snow to cover the exhaust port or I cool the tripple pipes down with snow instanly.....I hope this helps!!!!!Rob

P.S I am going to install a exhaust deflector on my SRX and I am also going to make removable vents out of plastic that go into the vents on both the belly pan and under the bumper. I also would like some other covers for the first of the vents on the hood. That way I have a chance when I slow down when I am in real deep powder so I can pick up speed again without bbbbboooooooooogggggggggggggggggg!!!!!!! I will warn any one that is going to make vents. You are not going to want to run them when you don't have to. There is alot of exhaust heat that is generated by tripple pipes and by restricting air flow you do run the risk of melting stuff......so enter at your own risk


Let me know what you guys think
 
I would try to use pre-filter material on all the hood vents, that way you'll still get air flow. You'll probably have to wipe them off on occasion after getting back out of the powder. Maybe the heat would help some with melting it off too.

Does anyone know if anyone makes and sells these for hood vents? The filter would have to have some sort of stitch around the edge or it would probably just tear from contact with the edge of the screens. I've thought about trying nylons, but think they would still just shred. I can hear it now, "Oh, no, I've got a run in my nylon!" :rofl:
 
Msrx

Since the SRXs have factory insulated pipes and my SRX ran in the deep snow with the hood off snow covering the complete mtr I don't think it is a pipe cooling problem. I noticed every time it bogged there was snow all over the hood and steam was comming out. Since steam expands a gazzillion times I vented my carbs out to my handle bars to check out the idea that under hood pressures were pressurizing the carb float bowls and the sled was going rich because of that. ( 98 MSRXs vents dropped into the bellypan ) It worked a lot better but not perfect. I was going to competely seal the airbox ( the drain holes in the bottom of the box) but I blew my crank again and traded it in. Maybe you are having the same problem even though you are vented to the air box. Seal up that airbox and try that out. I'm curious to see if that works.
 
Gild, very interesting idea & an easy fix if that's it. I haven't ever paid attention when I had the air box off, didn't realize there were drain holes in the bottom but that makes sense.

To answer my own question about pre-filter material: I looked through a JR Graham book and saw that they have pre-filter material for sale in three different sizes. I mentioned cutting it to a riding buddy of mine and he said he has successfully cut it before without fraying or having it come apart. He heated up a small nail until it was red hot and then used it to "cut" the material. Melts the edges together nicely.
 
I think Gild has come up with the best answer yet.

Think about it. The density of steam is next to nothing compared to the below-freezing air that is normally entering the carbs. One good hit of powder into the hood and suddenly your nice, cold, dense air is instantly steam. Your A/F ratio would go to hell in an instant!

Great thinking! ;)!
 
Lets say that I don't want to play with my air box because I think that the factory box is a lot better when it come to keeping my jetting constant in all temperatures. I ride from 50 above down to -40 degrees. I have also talk to many people that say that keeping the airbox stock will make the best hp in all temps and climates......with that said if I could get the snow to not touch my pipes and turn into steam I would have it.....where do I get prefilter material and how will it stand up....I don't even have a prefilter on the airbox now and I don't have any problem with the sled even with snow coming down at 2 inches an hour. Last night it ran great with snow dust in the air so much that i could barely see....

what about rag wool socks like I have read that ( I think that theblues runs in his ram air vents on his viper) I could paint that white and it is durable material..... I could simpley hole them on with some zip ties!!!!

I think that as soon as you got out of the powder the heat from the sled would melt all the snow off the prefilter/rag wool material. And like you said above atleast the sled is recieving some air flow compaired to plastic......


I also know for a fact that I need a exhaust deflector.....I came to a stop in snow that was just up to my bumper and the vents were closed off so there was no snow in the engine and it bogged until I got out and was moving....

I think we are getting close guys I know that I need and exhaust deflector and some way to let the vents breath and still get the majority of the snow to stay off those pipes!!!!!!!!!!!

Let me know whatcha think!!!!!!!!!!!!!!!!!!!!
 
Mnt-track: I agree on the steam part, that was one of the first things I was thinking. But then I read where several people have blocked all their under hood air and it wasn't the cure all. An interesting thought about this though is the drain holes in the bottom of the box. Maybe its still drawing in steam from there?

I tend to think like RIVERRUNNER and don't want to have to block the under hood air if possible. I also ride in a wide range of temperatures. Taking under hood air will keep air temps going to the box fairly constant, although maybe it doesn't affect it as much as we think. The other three main brands of sleds all take outside air only, all though the Ski-doos have DPM. My friends RMK takes only outside air and he never has any troubles. A K MntViper is taking under hood air if I remember correctly, and has solved his bog problem. The main difference seems to be his pipes are dipped as opposed to mine only being painted. That and he doesn't run his carb heaters and I do, but I will be turning mine off this year. I truly think that blocking the hood screens with pre-filter material should solve this, we all agree that when snow hits the hood the problem seems to start. Like RIVERRUNNER said, they run fine with snow dust in the air. It just seems to be when a wad of powder hits the hood screens. Since snow entering the hood compartment seems to be when the bog problem starts, why wouldn't keeping snow from getting in solve it? I know that Gild said he ran with no hood and snow everywhere, but here's my theory on that (for right now, anyway): the entire surface of all the pipes had snow on them, so there was no rich condition created from ONE pipe getting cooled.

Anyway, whether its steam, cooled pipe, spark grounding/arcing in the caps, if no snow can get under the hood...
 
I run a Bender 4X4 and SLP can, both have a heavy ceramic coating, as does my manifold. I run under-hood air and never run with carb heat. I do have a small dab of high temp RTV in my spark plug caps, and I do have the factory '05 exhaust deflector. I don't seem to have any bog issues.

I don't think snow has much effect on the air/fuel mix unless it chokes off the intake. If it turns into a massive cloud of steam under the hood, you'll lose your air density. With no hood, the steam would not be confined and thus not be much of a factor.
 
Steam

What I Believe is that steam is increasing underhood pressure which in turn pressurizes the float bowls causing sled to go rich. It has nothing to do with air intake density. If the vents are plugged hood pressure will increase. On the older sleds SnowTech mentioned that the SRXs under higher speeds went rich because of the change in under hood pressure. I am not sure but I thought the Viper was vented to the airbox so any underhood pressure spikes caused by steam would enter through the drain holes and pressurize the airbox causing an instant rich condition which causes the bog.This only happens witha totally covered hood and a shot of steam that is why with no hood there is no change in airbox pressure no matter how much steam is created.Then you have an air snow injestion problem.
 
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