Deep Snow BOG

[JonezyBones]

Ok so my buddy has an 04 vertical escape 800 and been going through some gremlins for a while now. Sled runs great on the trail but the minute you dive off in deep snow it looses all power sputters and then you get stuck.

SO we replaced the temp sensor and then the det sensor. Problem still exists. This engine was just rebuilt. (Coolant belt broke and cooked the engine) It also has slp twins on it. The exhaust isnt in the best shape. Missing gaskets and some repaired holes. After running the sled pulled the plugs and mag side was light brown and pto side was dark. Anybody have any ideas on what could be the problem. Thanks!!

 

[BILTIT]

What jetting/clutching, etc?

 

[2Quickrides]

How deep of snow? Is it possibly sucking snow into the intake? Or plugging the filters?
Did you check the plugs immediately after running in the snow or the trail?

 

[JonezyBones]

What jetting/clutching, etc?

Not sure ill have to check with him tonight. Its ran great before with the same clutching tho...

How deep of snow? Is it possibly sucking snow into the intake? Or plugging the filters?
Did you check the plugs immediately after running in the snow or the trail?

Anything over a foot it seems. It doesnt seem like its sucking snow because we've addressed that issue and last ride we went on it was a wet fluff and it wasnt coming over the hood. And yeah kinda right after it was doing the bog.

I did a search on the issue and someone was saying a sacked out secondary spring could cause the clutch to open prematurely over loading the engine. Something like this sound right?

 

[whoisthatguy]

Maybe it lost or flattened the external exhaust pipe snow deflector. They tend to flatten with age and then split the plastic around it's attachments. They bend back with a couple of adjustable monkey wrenches, but you need to remove it first. Then you just use some stainless steel #10 stove bolts with nylon lock nuts and large SS washers, to fasten back to the same holes.

It looks like your PTO side is running rich. Could be a problem with the needles. Like they weren't setup the same. Main jetting usually effects the higher rpm range. Twin pipes are problematic. Put in a single SLP pipe if you can find one for the right price.

 

[Goinboardin]

I would take a look at the exhaust deflector as Whoisthatguy suggested.

Check the jetting, but my finding was that even with the twins that motor is not super picky. I have run 340s,330s,320s, and 310s in the Crested Butte area with my 04' 800 and SLP twins. 310 was best but not like I was bogging with 340s. Stock needles in the second notch from the top, good fuel but watch for deto and enjoy. If jetting is the same in each, check compression, maybe its low on PTO side. Just want to see even compression, if it runs well and they're both at 120psi its fine.

Sacked secondary would indeed open the clutch too early, and cause a bog.

Twin pipes are not problematic. Keep those.

Another guy on here had this same issue like a week ago, he replaced clutch springs and sounded satisfied. Read this: http://www.snowestonline.com/forum/showthread.php?t=336748

 

[whoisthatguy]

When I installed new rings, compression measured at 145 psi. When they reached 125 psi, I changed them out. The Pro RMK have lower compression.

 

[Goinboardin]

What altitude, what head, what temperature? I've seen 150 on my motor in MN, 120 in WY. It makes a big difference.

Compression is a good measure of relative engine health on the same engine. Used in the way Whoisthatguy did is the correct way. Take a known healthy reading, and in the future compare against that reading (same gauge, similar alt. & temp for a valid comparison).

 

[BILTIT]

As reference, i have 140psi at 2200' with a 1200mile engine.