RPM fluctuation w/ elevation

[Snowbird11]

i've been tracking my trail rpm's closely for the last 8 rides and notice a strange trend. at 8k i'm seeing 8100 to 8150 and above 9k i'm getting 8250 to 8300. around 9600 to 10k i drop back to 8150 which seems more realistic. the surface conditions have been consistent and i haven't noticed belt slippage at speed but can't rule it out. this occurs both going uphill and back down to the truck.

what could be a cause for increased rpm at higher elevations?

 

[sledr900]

Did the temperature change?

 

[Snowbird11]

Did the temperature change?

Yes but with a moist adiabatic lapse rate it should only be around 5 degrees fahrenheit.

 

[rx1tonofun]

i've been tracking my trail rpm's closely for the last 8 rides and notice a strange trend. at 8k i'm seeing 8100 to 8150 and above 9k i'm getting 8250 to 8300. around 9600 to 10k i drop back to 8150 which seems more realistic. the surface conditions have been consistent and i haven't noticed belt slippage at speed but can't rule it out. this occurs both going uphill and back down to the truck.

what could be a cause for increased rpm at higher elevations?

You're clutching works best at 9000 feet. Below that you're actually slipping the belt and it's acting like a soft over rev. I'll bet it comes back up if you ease out of the throttle. There's a post by TRS explaining the Axys clutching, it's worth a look!