900 RMK and Swithchback track speed

[sleddude]

What track speed are you getting and what setup do you have?

Wondering what track speed you guy's are getting climbing in a 1.5ft or more of fresh. I read an old post in the 900clubforum from High-velocity that he tried a 70-44-.46 helix and was getting 51 to 55mph track speed (in pretty heavy deep powder), I think he had SLP pipe set and reflash and was using MTX weight combo of 79grams.

The reason I'm asking I get 42 or 43 mph track speed on a fairly steep climb with a good run at it first in 1.5 to 2ft of fresh of heavy Washington cascade snow. But always looking for more track speed.

Also the front cooler and track clearance is pretty tight maybe 1/2 inch or a little less. Is it possible to either eliminate the cooler without cooling issues or go another route and maybe do the F-Bomb mod to the 166 track and cut off 1/8 of an inch of track tips to evacuate the snow and gain track speed?

My sled currently has 66-42-.46 red/pink in secondary and titanium spring (same as BLK/GRN stock spring) with 10-72 in primary. With SLP pipe set and reflash and about 50lbs removed from my sled. Hits 7750 RPM consistently.

 

[Danbot]

when I trimmed my 2.4" track on my 900 (just past the nubs) I gained about 4mph track speed in the deep. It made a notable difference.

 

[sleddude]

That sounds like a pretty good mod to trim the track tips and gain 4mph track speed. I don't remember what track you had Dan 151? Happen to remember what track speed you would get? I know your sled pulled strong what weights and helix were you using?

That would put me at close to 46 to 47mph track speed so just looking for a few more changes to try and get closer to 50. These 900's have so much torque I think 50 to 55 mph isn't asking too much out of them.


Thanks
Mark

 

[Z-Man]

80 +

 

[94fordguy]

80 +

I don't think he was asking about turbos, LOL!!!

 

[High Velocity]

sleddude, you are correct. My '06 would consistently pull over 50 mph track speed, irregardless of whether or not it was light or heavy powder. I haven't had that sled since the end of the '10/'11 season (riding a '12 Pro) and still miss the shoulder-wrenching torque of that machine.


Done fishing. Let's go sledding !!

 

[Danbot]

That sounds like a pretty good mod to trim the track tips and gain 4mph track speed. I don't remember what track you had Dan 151? Happen to remember what track speed you would get? I know your sled pulled strong what weights and helix were you using?

That would put me at close to 46 to 47mph track speed so just looking for a few more changes to try and get closer to 50. These 900's have so much torque I think 50 to 55 mph isn't asking too much out of them.


Thanks
Mark

Yup, 151 x 2.4, If I remember correctly I went from 47 to 51mph with the track trim. It also hooked up way better in set up snow. The dry fluffy stuff saw a slight increase in traction from the extra trackspeed. I did this well after I rode with you, so you saw my 151 performing before that change.
Here's what I remember about my setup:
-19/42 in the chain case
-10-68's pushing the blue pink spring
-#419 helix I think, was recommended to be by Carls in 08, dont recall the secondary spring.
And of course my engine was stock aside from plugged VES hose and oversize VES ports, and plugged decomp holes.

 

[guidoxpress]

Get a lower helix..

58/46.46 and also get the team black/white secondary spring.

The red pink spring doesn't have enuf spring tension to create the proper back shift and allow for full shift out.

I trimmed all the tips off all my sleds tracks last year ..love it

Could also be track tension too tight/loose..belt deflection not set right

 

[sleddude]

Track speed improvement

Just an update. Well I installed the steep 70-44-.46 helix and saw my track speed pick up to 47mph on a couple steep climbs in early spring deep snow. An improvement from 43. Cool!

Only trade off is I don't feel there's as much torque right off the line and there's hardly any back shifting when you come down a hill, reminds me of my stock M7 just grab the brake cause when you blip the throttle nothin happens, no engine breaking at all. I think either I need a stiffer secondary spring maybe black/white, insted of red/pink. Also I'm 19/42 for gearing wonder if gearing down a touch more would help?

One more thing. I still can barely put a finger between the track and front track cooler and don't want to trim the track. Is it robbing HP from the sled? Is the front track cooler necessary? How much cooling does it provide? The newer Dragons and pro's don't have them I think...?

Thanks
Mark