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Adjustments for altitude?

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13 Apr 2006 23:31 #39402 by dannyh
Adjustments for altitude? was created by dannyh
I posted a similar topic to this one a few months back, however things have changed a bit. I just took the carbs off my bike (82 550 C3 Ltd). I cleaned out the float bowls, and replaced all of the jets and little brass fittings on the float bowl side of the carbs. I also replaced the mixture screws on all four carbs. I can't get all of the screws out of the slide so as to get to the main needles, (the ones with the notches in them).

I recently moved from 4500 feet to 1800 feet elevation. Am I going to have to re-jet my carbs, or move the clips on the main needles?

In regards to the ide mixture screw, (the ones that are factory covered), how many turns do I back them out from the seated position? They were about 1 1/4 turns out before I tore the carbs apart. But they were set for 4500 feet.

What adjustments do I need to make to my carbs? Keep in mind that everything on the bike is stock, and I just moved from 4800 feet to 1800 feet elevation.

ANY help or advice would be much appreciated.

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14 Apr 2006 05:54 #39432 by wiredgeorge
Replied by wiredgeorge on topic Adjustments for altitude?
I haven't the time to look up what type carburetors you have on your bike. Are these Tekei? Are they CV or round slide? Rejetting for 4500 ft will probably help fuel economy and power some so I personally would rejet but the bike will run without rejetting.

wiredgeorge Motorcycle Carburetors
Mico TX
www.wgcarbs.com
Too many bikes to list!

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14 Apr 2006 06:57 #39451 by dannyh
Replied by dannyh on topic Adjustments for altitude?
Wired George? The guru himself? Wow, I feel honored.

I believe they are round slide. The rebuild kits say Keyster on them. I bought them off e-bay.

You say it will run. Will it run poorly or will it run just fine? Also, about the idle mixture screw. How many turns out from the seated position? Thanks again. I-ll let you know how it turns out. :)

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14 Apr 2006 11:48 #39521 by wiredgeorge
Replied by wiredgeorge on topic Adjustments for altitude?
I have a formula for computing jetting changes vs altitude. The Keyster brand is the Japanese company that made the carb kits. Do the carbs have big round tops or are the tops about 2" long and 1" wide? Do the carbs say Tekei on the side? What jets were in the Keyster kit and what does the buykawasaki.com web site say are the OEM jet sizes?

I would say your pilot jet is OK replaced as-is. I would leave the jet needle clipped as it is (especially since you can't get the screws out bwhahaha) and cut the main jet back a size or two... You can use regular small headed Keihin mains as they have the same thread and the hole sizes are the same as Tekei as you will never find genuine Tekei jets.

If the bike is sluggish at altitude, it is generally because it is too rich as there is less air making the air/fuel mixture more oriented towards rich. I have ridden stock jetted bikes up to 10K feet and above and they work OK but will feel sluggish up at the top of mountains... at 4500 feet, it won't be bad but I suspect you will be wasting a bit of gas.

wiredgeorge Motorcycle Carburetors
Mico TX
www.wgcarbs.com
Too many bikes to list!

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14 Apr 2006 16:11 #39564 by dannyh
Replied by dannyh on topic Adjustments for altitude?
My carbs are the ones that are 2 inches long and 1 inch wide. They say "TK Carburator Co." on the side to them. The jets they gave me are stock size. Main Jet is a 90 and the pilot jet is a 32.
Since I am at 1800 feet, it shouldn't be too much of a difference than at sea level, right?

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