I have a 99 Big Bear and have discovered that it is nearly helpless at 10,000 ft.

To rejet for altitude, is it a simple matter of screwing the old jets out of the carb and replacing them with hi altitude jets? Or are there other adjustments to to be made?

 

I do a lot of high elevation riding myself and do notice a decline in performance when up there...I posted a good while ago inquiring about Dial A Jet.I'm wondering if this wouldn't cure the problem...Anyone out there with experience with the system? ATV Connection is supposed to issue an update on their tests on Dial A Jet but thus far haven't.

2000 450ES Red.

 

Here at 6,000+ feet we just adjust the main needle jet, its that long needle at the end of the throttle sleeve (inside the carb). Unscrew the throttle cable from on top of the carb, at the bottom of this assembly is the jet that I'm talking about. When you disassemble this you'll find some notches at the top of the needle itself. Move the clip to the top notch, which makes for a lean mixture. People get confused with altitude, your engine runs richer with increase of altitude, so by putting the clip in the top notch, the needle jet sits lower making fuel entering the carb harder. Any way that's the way we do it here. You're lucky that your quad is a four stroke, they're much better about altitude changes.

 

You loose 3% of your power for every 1000ft of elevation.You need to change main jets also maybe weights on clutch.

Later COB

 

Thanks for some of the info, but I was looking for specific instruction as it relates to the 99 Big Bear for 9,000+ altitude. This isn't a belt drive auto that requires clutch weight changes.