high altitude jetting question

[†2005 400ex†]

Im goin on a trip to colorado riding in a couple of weeks and i need to jet my carb for elevations from 9000 to 12500 feet but my service manual doesnt give a jet for any higher than 8000 feet. Should i just run the 142 or do i need a different size?My quad is bone stock except for skidplates.

[GPracer2500]

I'm not sure what's right for those elevations. 12,500 is really getting up there. One thing you can do to help get air into the engine is to remove your airbox lid. That will help if you find you're too rich.

I'd say if you also had a 135 and 140 you'd probably be covered (with also using your airbox lid on/off as needed.)

Really, I'm just guessing though. Whatever happens, let us know when you get back what jets you used and how it ran way up there. Be ready for a significant drop off in power--even if it's jetted right.

[†2005 400ex†]

alright that sounds good, yea we are going to be riding over haggermams pass which is at the continental divide, its definately up there