Mtn Riding questions

[ViperXC]

Just got back from the mtns and have a couple questions for anyone that wants to answer. What RPMs should a Viper be running in the mountains? Can only remember the one for now. Thanks


My other question was about snow evacuation. When carving in bottomless powder my sled would start to bog down until I got back on a track. Is this due to not enough clearance between the track and front heat exchanger maybe? Causing the snow to build and not evacuate quick enough?

 

[151Viper]

Viper with no pipes should be about 8,400 rpm's. Were you getting that?

 

[ViperXC]

Yup, that's good, I seemed to be running about 8500 tops with it clamped to the bar.

 

[A K MtnViper]

if you are in deep powder you could be bogging from snow getting to your air box filter, read the thread on bogging.

 

[ViperXC]

Not deep enough or maybe not soft enough for snow over the hood and I was carving left to keep the exhaust open as well.

 

[A K MtnViper]

Assuming good spark plug caps and jetting. The most likely cause is not back shifting fast enough needs more twist. I run at 100 degrees at 8,500 to 12,500 feet.

 

[snomoguy]

AK has probably hit on it, not enough back shift, I run mine at 80 degrees with a more or less stock viper. However you are somewhat right about the snow being carried thru the tunnel. If you look at the tunnel of a viper with a 2" track there isn't much room. The mt. viper has an inheritant trenching problem and I somewhat blame it on not being able to rid the tunnel of snow. One way to cure the problem is to drop and roll the chain case, however this being somewhat expensive project. Another way is to port the tunnel, allowing the track to rid some of the snow before it is carried thru. However you're problem as AK said could be one of several problems including jetting and or clutching. The viper will run a leaner jet than the book calls for, and will run a heavyer primary weight than the book calls for espescially if you gear back a tooth or two.

 

[ViperXC]

Thanks for the pointers. With the porting, are you actually referring to the track though and not the tunnel? I will have to look into the twist some more, will that be fine to run more twist here and in the mountains or would I have to change it from low to high elevation rides? I do have it geared to 20/38 right now and may go to a 40 bottom gear. Thanks again everyone

 

[zack19]

whats the stock gearing on a mtn viper? I have an 04 mtn viper and it seems a little lower than it should.
i was experiencing the same problems and was thinking of a different tapered helix to help with this but am not usre where to start for angles or setups,...got any pointers?

 

[Viper_Jim]

I believe the stock gearing on a Mtn Viper is 21/40

 

[dirtjumper895]

Sorry to bring up a thread from the dead, but if we were to go to a 7 tooth driver, running a 2" track, would trenching be less because of more room between the exchanger and track? Would it be worth changing?

 

[mod-it]

Viperxc, your sig says you have an '02 Viper. Did you long track it? Most of your problem could very well be gearing if so. What length track does it have?

Viperjim is correct on the stock gearing for a Mnt. Viper. My Viper doesn't trench at all until I lose lots of momentum, then it's time to turn out. Hard to compare, as mine has triples on it, but I'll bet you need to drop your gearing some more. It needs more torque to turn your track when it has a heavy load on it from deep powder. Keep an eye on your track speed when climbing in powder. I feel this is the best way to see if your changes are improving it or going the wrong way.

 

[yam_apex91469]

i don't know how it compares to a viper, but my 151" srx doesn't trench too bad at all - i'm running 8T extros, 2" ported track, heads, VForce and 21/42 gears. The gearing helps keep the track speed up in the pow - there's probably only about 1/4" clearance from the front heat exchanger