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Hot DRY jetting.

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My JD kit comes with suggestions for warm/humid jetting, and for cold/dry jetting.

What about HOT DRY??? Like Las Vegas 110 degree weather, with insanely low relative humidity??

Anyone jetted to these condition and can give some advice on a good starting point?? bike has Drd full system.

Currently on red needle, middle clip, 185 main. Seems ok to me...but then again, the only WR250 i have ever ridden is MINE...i have no basis for comparison.

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i don't think you jet for humidity, i could be wrong but more humitity accually gives a hair more pop, you see, wet air in alot harder to compress, so it will up your compression ratio, as for the hot, you just jet for the temp and forget about the humitity. other ppl will probably flame me and say "i wouldn't trust this kid" but i know my stuff.

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you see, wet air in alot harder to compress, so it will up your compression ratio.

Need I say more?

Have you tried the 180 MJ? You would have to richen up your fuel screw to.

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Humidity, or lack of it,has less of an effect on jetting than temperature or altitude. Very cold air tends to dry itself, and that may be why they mentioned it. If JD makes a distinction between cold/humid and cold/dry, you could use that info to base a correction on.

Humidity displaces oxygen (and other gases), but does not reduce the density of the air. Air flowing through the carb will draw roughly the same amount of fuel up through the jets whether it's wet or dry, but since there is less oxygen in wet air, the mixture is very slightly richer.

Personally, I don't pay much attention to humidity.

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