Altitude / Elevation HP loss

I've been trying on and off for a long time to get my '03 WR450 to get great power, but it just isn't working. Bear in mind I live at 6500' elevation so I know the power is going to be down, but I just find it hard to believe it's down so far. My WR has all the power mods:

YZ cam

opened up the airbox

GYTR titanium pipe with quiet tip

shortened throttle stop

gray wire,

JD jetting kit

etc, etc

I have tried a lot of jetting combinations but haven't found one I'm satisfied with. I ride occasionally in Oklahoma (much lower elevation) where I had it jetted around 165 with 45 Pilot. It was a completely different bike. I could pull roll-on wheelies upto 3rd gear. It still wasn't as good as my old YZ426, but I didn't have time to dial it in further and didn't have the YZ cam then. When I got back to 6500' though I couldn't get a wheelie to save my life! :applause: My latest effort to get back this lost power was to put in the YZ cam and a 13 tooth front sprocket. I also tried some YZ jetting suggestions on TT. So far nothing has worked. I can still just pull a wheelie in 1st gear. That with a 13 tooth front sprocket! The power right now just comes on way too slow. It never has that low end kick that I want (or used to have). Am I just asking too much for roll-on wheelies in 3rd gear at 6500'? Or is there something I can't figure out wrong with the bike? My latest suspicion is that there is something wrong with the fuel mix at low throttle. But I'm just bummed. I know there's a ton of info in TT about tuning the WR but really I'd just like to see if anybody else has this problem at high elevation. If that's just the way it is I guess I'll live with it, but I want my arms ripped off again!

A rough guide is that you loose 10% of power for each 3,000 ft increase in elevation. The air is less dense so it cannot support the burning of as much gas as at sea level.

Ride on


you probably need to keep messing with your jetting.

in fort collins, Colorado we're near 7500ft and our bikes work just fine.

i believe I run a 165 on my '96 cr250r and thats good to about 9000ft

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