The infamous powder bog

After today I might do something with the exhaust deflector. Still not enough air but I think the two are linked.
 
Need to come up with a scoop or something so it can draw air from a vertical filter and snow wont stay on it. My filters behinds the windshield always have snow on them in powder.
 
I think the biggest part of the problem is the steam off the pipes getting to the airbox. I had sealed up the big spots with foam but the spot where the dashes comes together must have leaked. Duct tapeon all the joints I could get too. Drilled the dash like Hartman, put 4 holes for a rebar tree. Made domed covers out of prefilter velcroed down. Road in deep powder all weekend ran great. Only bogged when exhaust was restricted on take offs. Have to look into a bigger deflector. Sure was fun not having to fight the bog.... Got some snow on the air box filter a couple times just had to clean off a couple of times. Pre filter on the air box always used get plugged up and wet= no air. I'll just have to clean the filter a couple times a ride..
 
I should have posted this long ago, but finally just got around to it.

Maxeater, I think you could have hit the nail on the head. I wonder how well everyone is "sealing" off the under hood air. I had read about everyone blocking the under hood air and for many it didn't seem to help, so I hadn't ever tried it yet. I was waiting to hear a definite cure.

I finally went ahead and taped off all my under hood air this last season, after I got my stator problem diagnosed and fixed. I only made three more rides after that, but the first one was in McCall on Easter weekend. Couldn't believe how good the snow was, gobs of powder. It was 9*F when we unloaded. On a side note, my brother-in-laws Poo 900 had a ring come apart two miles from the parking lot, I tried to tell him how much trouble they have been having with those, but he wouldn't listen. Anyway, my sled ran awesome! I was shooting banks, which when you first start into them they throw gobs of snow up onto the hood, and had no powder bog problems the whole day. Hill climbed, carved meadows, hit drifts and blasted snow clear up over the windshield, never had a problem. Like you said, maybe a very slight sputter when I first gouged into the banks/drifts, but then cleaned right out and pulled peak rpm's with no trouble. When I taped up the hood, I noticed that around the lense for the head light you have to pay pretty close attention or air could still come in from there. It was only one ride, but the powder was really light and the kind that I've always had trouble with before. Seems like thoroughly sealing off the under hood air and having flow-rites in the dash has done the job for me (knock on wood!!!).
 
Bog

I converted my 01 srx into mt srx 151, I fought this exact problem for a year. With no bog sled did great, but the bog thing kinda suck when in 3-4' of powder. Tried sealing anything and everything. It helped but didn't solve it totally. Sold it and ride 01 MM, bog is gone. Not sure what the major difference is? :letitsnow
 
I have read this thread top to bottom and implement a lot ideas on my own sled. The only thing else I want to do is change my spark plug boots. Which boots should I use? stock or NGK.


On a side note I had a old yamaha jet-ski once that would bog when riding it hard. Long story short I went though everything on the motor, intake and exhaust only to find that I was building up condensation between the spark plug boots and the spark plug. Got new boots and it fixed the problem. I used NGK boots then.
 
Well, I don't know why, but my bog seemed to be cured last season after I blocked all the openings on the inside of the hood so it could only take air from my flo-rites in the dash. I still believe that people could be missing some of the spots underhood air can get in through the hood, there were all kinds of nooks and crannies I had to tape off. The ONLY other change I really made was I put some di-electric grease on the plugs, maybe there is something to the plug cap idea? I also think that AK MntViper is correct in adding more twist to the secondary. I'm not running 100 like he is, but I'm running the 80 that SLP recommends for riding over 6000'.

I think a good cap to use if you want to seal the plugs off is the hard plastic NGK caps. They come with a rubber piece that seals between the cap and plug.
 
bog gone

You got it modit , seal the airbox completely and take intake air and carb vents outside of the hood ( also vent airbox water drains to the outside ) and then you can open up your vents and cool your engine. you won't have to worry about the steam anymore.
 
I get misunderstood on this a lot. What I mean by "blocking the underhood air" is NOT the outside vents that let cold air into the engine compartment. I mean the openings in the under side of the hood that allow air to be sucked from the engine compartment up and into the air box. The air box seals to the hood when shut, but the two triangular holes, two rectangular slots, opening under the headlight, and a lot of little nooks and crannies around these let air be pulled from the engine compartment up through the hollow gap where the forced air induction chamber is and into the air box. Cold air is still able to enter the engine compartment, but the forced air induction chamber is completely sealed off except for air coming from the flo-rites in the dash and funneling straight into the air box.
 
river runner if you have a stock hood and airbox they meet at the front of the airbox where the foam is glued to the airbox,if you have a cold air kit it also has more foam that gaskets airbox to hood
 
mod-it said:
I get misunderstood on this a lot. What I mean by "blocking the underhood air" is NOT the outside vents that let cold air into the engine compartment. I mean the openings in the under side of the hood that allow air to be sucked from the engine compartment up and into the air box. The air box seals to the hood when shut, but the two triangular holes, two rectangular slots, opening under the headlight, and a lot of little nooks and crannies around these let air be pulled from the engine compartment up through the hollow gap where the forced air induction chamber is and into the air box. Cold air is still able to enter the engine compartment, but the forced air induction chamber is completely sealed off except for air coming from the flo-rites in the dash and funneling straight into the air box.
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sorry... but I just can't get around the "forced air induction chamber"....

The hood seals to the airbox when when the hood is shut.... The airbox fresh air then is pulled through the coarse foam/plastic filter above the handlebars but below the dash platform (the filter looking right at you with hood closed sitting on the seat)....

Where else is this air coming from?... The forced air induction chamber is what exactly?...

Also, not sure how air from opening under the headlight gets to the airbox?...

2002 MM 700 completely stock.... please help me out with this since I might be missing something...

I will have another good look under the hood tonight, however...


thanks TJ
 
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The forced air induction chamber is on a Viper. On the short tracks there are openings on the outside of the hood on each side of the head light. On top end air is driven through them and channels right onto the top of the air box resulting in what Yamaha claims is a 3hp gain. This is also on a Mnt Viper, but the outside openings are blocked off from the factory with plastic so snow can't get in.

I'm not familiar with a MM, but on a Viper there is basically a hollow area between the outside of the hood and the inside (headlight, bottom of dash). The air box has foam around it so the hood seals when shut, BUT the openings to the hollow area allow air to be able to enter the air box anyway. I have no idea why they would seal to the hood, but still allow under hood air to be able to get in. To my knowledge, all other manufacturers only take outside air. I've never heard of a powder bog on any of the other three brands of sleds either.
 
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mid season last year, all four major brands being represented, in about 6' of fluff, all brands were having issues with powder bogging. the group consisted of 2 08 skidoo xps, an 07 m1000, 07, 700 and 06? 900 polaris and of course, several yamahas. at any given point, we all had issues. leads me to believe in certain conditions, you can only push so much snow, and it doesnt matter what your on, its going to happen. thought it was just my sled, but was relieved to see the other brands suffer from the same snow ingestion.
 
snowdad4 said:
mid season last year, all four major brands being represented, in about 6' of fluff, all brands were having issues with powder bogging. the group consisted of 2 08 skidoo xps, an 07 m1000, 07, 700 and 06? 900 polaris and of course, several yamahas. at any given point, we all had issues. leads me to believe in certain conditions, you can only push so much snow, and it doesnt matter what your on, its going to happen. thought it was just my sled, but was relieved to see the other brands suffer from the same snow ingestion.
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and in all that snow,how did your msrx perform?
 
srxhair said:
and in all that snow,how did your msrx perform?
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i dont have a msrx, per say. my sled started out life as a 121 srx. it works quite well. but i have done a lot of stuff to it. this year should work even better. in conditions described above, all you can see is a helmet moving through the snow. that particular day we were sure glad to see a groomer after about 3 hours of trail breaking and leapfrogging leaders, it was nice to have a way out.
 
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