Doo 850 and Cat Alpha losing 1000rpm!


Undefeated mountain clutching champ of the world.
Lifetime Membership
Oct 14, 2008
We had a cool thing happen while spring riding at about 5000ft in Whistler, BC, Canada.

The temperature was kinda warm about 8 degrees Celsius/46 Fahrenheit. Blue bird day.

In three separate occasions, same hillclimb, both sleds lost 1000rpm, 8000 to 7000 rpm.

I told my friend I just lost 1000rpm on that climb. Then he told me he also lost 1000rpm. The funny thing is that on other some other climbs, the sleds held rpm.
This happens three separate times, at the same time on the Doo and Cat.
I would have thought it was a manufacturer issue but all I can figure is the warm temperature or barometric pressure affected both sleds the same.
Thinking about it now, it was kinda cool to see how both sleds are affected in the same way.
I hereby leave you with this odd situation to mull over for the summer!


Well-known member
Lifetime Membership
Oct 22, 2012
Deering ND
clutched for powdery snow and maybe it depended on what way the hill was facing if the hill had more sun maybe it was sticky and set up so they werent getting any track spin.
Nov 26, 2007
Elko, NV.
I see that in Northeast Nevada all season long, when you're +40 degrees you get a combination of variables that can cause some serious performance issues, high ambient air temp and high humidity can cause a tremendous drop in air density. When you combine that with high sheave temps and high belt temps you get even more performance loss. If you want your sled to stay on the pipe on those days you better have a variety of lighter weights in your pocket or you will cuss your sled all day long. I can run 66 gram weights in 20 degree air all the way to 11,000', in 35 degree air I need to run 64's, when springtime rolls around and +40 degree air is the norm I have to reach for my 62's and my heavier primary spring or I too will lose 1,000 R's. On some days it appears you will drive in and out of humid pockets all day long giving you the feel that your motor is on the brink of failure, there is usually a simple solution, take a lunch break, lighten up 2 or even 4 grams and rock and roll.
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