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makncan

6K feet Altitude jetting anyone done it?

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Hey guys,

First off I have an '03 WR450F uncorked exhaust that I bought a few months ago.

I've seen the formula thats posted to figure out jetting but I have to admit that I was totally intimidated to actually try and figure it out so I figure I'd ask around and see what others were running

I live in Chicago and I'm taking a trip to bear lake in Utah to do some riding where we should encounter altitude of approximately 6000 feet. I'm a relative newbie to dirtbike riding and just checked my main and it's a 175 which seems big but it was running decent.

Any info or help you can offer, I totally appreciate

Thanks

John

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Hey guys,

First off I have an '03 WR450F uncorked exhaust that I bought a few months ago.

I've seen the formula thats posted to figure out jetting but I have to admit that I was totally intimidated to actually try and figure it out so I figure I'd ask around and see what others were running

I live in Chicago and I'm taking a trip to bear lake in Utah to do some riding where we should encounter altitude of approximately 6000 feet. I'm a relative newbie to dirtbike riding and just checked my main and it's a 175 which seems big but it was running decent.

Any info or help you can offer, I totally appreciate

Thanks

John

Make sure you compare the temperatures you'll be encountering with what's "normal" for your home altitude, because that will make a difference as well. With comparable temps, if you're at sea-level, I'd expect a 2 jet size smaller would be ok. You probably won't go wrong with 1 step lower, either...I'm at 5k in Colorado and with my intake and exhaust opened up I run a 168 main and go up to 10k+ feet, although I think I could fine tune it a little more....

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Ok sounds like a good plan. I just picked up a 168 and a 160 today so hopefully Im set. Thanks for the help

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This will help

Jetting for Altitude and Weather

Keep in mind, it assumes your base jetting is perfect and the values returned are optimum (more or less) for the target air density. So if you are riding up from sea level, you need to figure jetting for say 3,000~4,000 feet to ensure the bike will run all the time

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I just got back from Colorado yesterday. My bike is jetted for sea level and it ran great. Hit 10k feet and higher several times. All I did was drop the needle 1 clip down to lean it out a tad, which I was going to do for the summer anyway.

I wouldn't bother with the jetting. It will run fine.

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