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snowman02

Changing Altitude and Jetting

7 posts in this topic

I know, I know, not another jetting question, but i think this one is just a little different. I live in Az. at an altitude of 380' I am planning a ride to the higher elevation, say anywhere from 4500' to 7000' how screwed up will my bike run? I am not certain what jets are in my bike, i have never had to do any jetting to it as of yet. It runs great now no problems what so ever. :thumbsup:

So what can i expect, and should I bring some jets with me just in case?

Thank you fellow TT'ers in advance. :thumbsup:

BTW: This is refering to my 02 WR426

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You'll be running pretty fat at that altitude. Give the jetting database a look see and that ought to give you an idea. However, you need to know what you have in there first...SC

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Thanks SC, thats what i figured. I'm just uncertain about my mechanics when it comes to these newer 4stroke monsters, and have never had the carb out in this beast. but i will have to learn sometime, and if anyone has any suggestions about the way to get to the jets in the easiest way manner would be helpful. I can see it looks like a biotch getting the carb out. :thumbsup:

Thanks

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You can do everything you will need to do without removing the carb. On the bottom of the bowl is an access plug that will give you access to both the main and pilot. The needle can be removed from the top with the seat off and the carb out of the boots and dropped down a little. To change main and pilot simply loosen the boot clamps and rotate the carb clockwise looking into the intake unitl you can see the plug well. You will need a small short (about 3-5 inches) flat screwdriver. The main requires a 6mm socket head. Hope this helps, once you have done this a few times it will only take a few minutes to change jetting.

Josh

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Thanks alot Josh. Great the carb doesn't have to come out of the bike. That is a relief. Now maybe ill go ahead a purchase the JD jet kit, and see what kind of trouble i can get myself into.....lol

Again thanks

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I know, I know, not another jetting question, but i think this one is just a little different. I live in Az. at an altitude of 380' I am planning a ride to the higher elevation, say anywhere from 4500' to 7000' how screwed up will my bike run? I am not certain what jets are in my bike, i have never had to do any jetting to it as of yet. It runs great now no problems what so ever. :thumbsup:

So what can i expect, and should I bring some jets with me just in case?

Thank you fellow TT'ers in advance. :thumbsup:

BTW: This is refering to my 02 WR426

I have the same bike. I installed a JD kit following the setting suggestions that come with the kit. When I ride at 800' I get a few small pops on declaration but I ride up to 6000' and it still runs strong. I did end up dropping my slow jet (to a 39 I think) because it would sometimes flame out when trying to get going again after making it part way up a hill climb. Here is my current setup:

Model (400 - 426 - 450): 02 WR426

Timing (WR-YZ): YZ with 03 exhaust cam

Main jet: 170

Pilot Jet: 39

Fuel screw (turns out): 1 1/2

Needle model/Clip position: JD blue needle postion #3

Airbox lid (on or off): Lid Off / Twin air filter

Pipe: Stock exhaust/insert removed

Altitude where you ride: So Cal 0-6000 ft

Temperature where you ride: 40-100

Degree of satisfaction: Runs awesome quick response/no bog

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A finger adjustable fuel screw is another good way to make quick adjustments. When I ride in CO we will start @ 6500 and sometimes go over 10,000. It's nice to be able to make quick adjustments during a ride.

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