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Old 05-27-2011, 10:51 AM   #3467
Luke
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Joined: Aug 2004
Location: Idiotville, OR
Oddometer: 4,115
Quote:
Originally Posted by IronSpadeCycles View Post
I hope this helps. I've purposely not just given you an ideal jet size cause every bike is a little different and your idea of "uncorked" may be very different than my interpretation. So if you know your bike is spot on at sea level and your intended riding area is on average 7000 feet, you would reduce the jet size by 4 sizes (7000ft/1750= 4) (Mikuni jets are in steps of 10 equals 1 full step and 05 is a half step) So if 162 was stock dialed in sea level jetting a reduction to 122 main is what they suggest, but again this is only a suggestion.


http://www.4strokes.com/tech/howtojet.asp

No wonder you were having trouble with jetting. Mikuni and Keihin jets sizes have nothing to do with each other. According to the manual, if your correct main jet at sea level was 162, you should run a 152 at 7000 feet. Not 122.

Here's the chart:
http://john.rushworth.com/Pics/XR400...Q/main_cor.htm
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