fuel screws deep powder bog

..SNAKEBIT..

..SNAKEBIT..

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May 2, 2003
Messages
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Location
NE IOWA
when running my Viper out west, IT WILL BOG IN THE DEEP
can have it WFO and it will start to loose RPM till the sled quits moving
any help????????????
can I turn the fuel screws in more? will it help?

02 Viper 136 x 1-1/2
CPR pipes, with head mod
exhaust deflector
8ek no rivets stk spring
43' helix silver spring 80' twist I think
19 top 41 bottom gearing 68L
9 tooth drivers
holtman Atacc installed
jets 162.5 162.5 165
pilots 47.5 47.5 47.5
needles 3th groove washer top & bottom
fuel screws 1.75 1.75 1.75
all stock carb parts
2 flo-rites, ram air filters, air box prefilter, 1-1/2" hole drilled in each ram air duct to dump air right into the air box
all under air inlet to air box are duct taped off, to suck only outside cool air, from ram air and flo-rites
and still tuning LOL
 
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Where and high are you riding?
If it is the snowies...........junk the ATACC and jet for altitude.
 
Snow deflector in front of the exhaust outlet? If you don't have one add one, sounds like that is what you're describing as a problem. The snow stops the exhaust flow and will choke the motor off.
 
sorry riding the snowies ? @ 7500-11000?
but also ride Iowa
I do have a Yamaha snow deflector on, the pipes stick out about 1/2" below the pan
 
Changing the fuel screws will virtually not affect wide open throttle at all, that is on your mains. They all overlap a little bit, but the change is minimal. Could be a powervalve problem, an exhaust flow problem as srxspec stated, could be a sacked spring in the clutch or a bushing binding up or just simply too much load for the conditions causing a bog and possible belt slip. What condition are your clutches in? Any black marks on them indicating a belt slip? When was the last time they were cleaned? How about powervalves cleaned and adjusted?
 
Valves cleaned and adjusted before each trip west
clutchs removed cleaned, different weights, helix & secondary spring installed
I do have a heavier primary spring ,black I think
no black marks to speak of
hill climbing it seems to rip, but in the deep even carving to the left it will start to loose power and continue to loose RPM's
every little thing I do seems to help a little? deflector ,florites, dilled out ram air, taped off under hood etc... just looking for that final FIX
 
OK snomoguy if I unhook the ATACC, what should I jet to?
are you running pipes? or know someone that is that can help
where do you ride? We try to ride all over the range will be staying in Centennial
are you speaking from experience or just typing?
and this is the CURE?
 
1st every Viper I put pipes on had trimmed the pipes flush with the belly pan & it helps.
2nd snow on top of the airbox even with the Pre-filter will choke out the engine, Heat from the engine will melt the snow & the water plugs up the pre-filter from whatever treatment they put on it & will not suck enough air & choke out like you have stated, Simple check is to shake out the filter & try again or simply remove & try, My prefilter sits in my trunk from the last time it plugged up & pissed me off.
Did you relocate the rear skid back? Deep snow can be a pain but the relocated skid helps the Viper get up on the snow & keeps the exhaust out of it.
 
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All of the common causes have been mentioned, but check your electrics out starting with the plug caps and coils and then working backwards.

I also suspect that the secondary. Once the sled quits moving or slows way down, what does the engine do? In fact can you give us an idea of what the rpm's are all the way through this "bog" cycle?
 
I'd start by looking at the clutch springs. Very often, when this happens the clutches are so hot you can't touch them. If this is the case, you need to figure out how to keep the clutches cool since hot springs go soft and can eliminate backshift. Check your driven pressure. Don't be afraid to bump the driven setting up to 90 degrees. An exhaust deflecter will really help and if you are going to ride deep snow you should probably have one. You say that when you carve it up on its left side the bogging starts. Pulling or carving the sled onto the left side should clear the exhaust and cause the bog to start to disappear. Tells me it may not be totally the fault of the exhaust. The ATACC is a great product and will maintain a tuning at most altitudes and temps. However, if you have ever had the sled on its side or upside down, fuel will get into the small tube that goes from the ATACC to the bowl vents. If this happens, the sled will not run very well, super rich, bogging and no power. Really shows up under heavy loading like deep snow. Simply pull the hose off the T that goes to the carbs and clear the fuel out of the line. Hope this helps you.
 
It sound a lot like it's shifting out on the secondary and not back shifting, I had the same problem with my V-max long track in the deep snow. It would bog down big time. I tightened the secondary spring and the bog was gone.
 
..SNAKEBIT.. said:
OK snomoguy if I unhook the ATACC, what should I jet to?
are you running pipes? or know someone that is that can help
where do you ride? We try to ride all over the range will be staying in Centennial
are you speaking from experience or just typing?
and this is the CURE?
Click to expand...

The ATACC will not compensate over 10,000 ft. Call them and ask! If you want more conclusive advise, stop in at Laramie at TNT, walk to the shop and tell Bob you have an atacc, then turn to the door and run.
Yes I am talking from experience. I own a cabin at 10,000 feet on the north end of the snowies near Turpin Resevoir and have been riding there for 30 years.
The atacc doesn't do to bad of a job with stock, but with all you have done to the air box.........it can't make up it's mind how to react.
Maybe it is getting fuel in it, I don't know, I do know that if you get rid of it and jet straight across at least you will illimiate that as a problem.
With all you have done to the air box and such I can only take a guess.
MJ 148.8(maybe 150 to start) PJ 50 PS 2-5/8 JN 2.5
I have a peak head (19cc) and a bender can with flow-rites, the rest stock. I run MJ141.3 PJ55 PS3 JN2
Not trying to be smart........just trying to save you alot of grief. Hate to see yami guys on the mountain broke down. Doesn't look good.
Spent all last weekend down there running gas and oil to a butch of flat land ski-doo riders who got to far away from a pit stop and didn't know where they were. 2 were out of oil and 3 almost out of gas and 40 miles of powder to go to the closest pit stop.
Good Luck
 
Sorry, should of been alittle more hospitable.
When are you going to the snowies!
If I can make it down.........your welcome to stay at our place sometime.
Only cost is bring your own food and pay for gas.
See ya on the trail.
 
I thought about triming the pipes, I WILL
I check prefilter alot!! open hood alot to let HOT air out
I really wanted to relocate skid, BUT some people on here said transfer sucked, and they would never do it again or redid it with longer extensions
so I went with the Tracks USA 144 tip up
the silver secondary spring seems really stiff (back shift wasnt good before this spring)

OK Ding, ring my bell and tell, me how to check plug caps? resistance? etc..
clutches used to get HOT, when I switched to the silver spring & yamaha belts good!

Just hate to start over with the jetting, when I go we ride and dont have much time to tune. thats why this is hard to fix. its rideable, climbs good etc. but in the really deep stuff it will bog
a stiffer primary spring wont help ill it?? also have 8cr weights I could try???
THANKS FOR ANY SUGGESTIONS THEY ALL MAY HELP!
 
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Well, I learned something. Snomoguy, didn't know that the ATACC would not compensate over 10K feet. Thought the ATACC would only compensate for 10K ft of change. My sleds are calibrated to 4700 ft and still seem to work acceptable in Cooke City but I will admit that Cooke City does not get above !0K ft. So I have no real experience to argue with. I'll take your work for it. Thanks.
 
..SNAKEBIT.. said:
I thought about triming the pipes, I WILL
I check prefilter alot!! open hood alot to let HOT air out
I really wanted to relocate skid, BUT some people on here said transfer sucked, and they would never do it again or redid it with longer extensions
so I went with the Tracks USA 144 tip up
the silver secondary spring seems really stiff (back shift wasnt good before this spring)

OK Ding, ring my bell and tell me how to check plug caps? resistance? etc..
clutches used to get HOT, when I switched to the silver spring & yamaha belts good!

Just hate to start over with the jetting, when I go we ride and dont have much time to tune. thats why this is hard to fix. its rideable, climbs good etc. but in the really deep stuff it will bog
a stiffer primary spring wont help ill it?? also have 8cr weights I could try???
THANKS FOR ANY SUGGESTIONS THEY ALL MAY HELP!
Click to expand...

The prefilter will work fine covered with lite snow on my sled, once the snow melts & the prefilter looks fine is when it acts up. The water plugs the prefilter & will not draw enough air. Never a problem untill riding in over the hood snow. I use the same filter on a funnel to keep water out of my tank when filling up with gas cans. Sounds stupid but been there & done that.
 
Yea snow over the hood, just the sound of it make me h*rd
been layed up (my foot) all winter just got a shoe on, and going west March 10
 
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