# Jetting formula for relative humidity

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Anyone have a simple basic formula for jetting relative humidity changes?

For instance on my 2 stroke it's basically 1 main for every 2000ft and a clip change every 2-3 mains.

In the fall here it is quite cool, 50's- 60's so you would expect to have to richen your jetting compared to the 90+ summer heat. But it goes from bone dry to 80-100% RH and I always find I actually need to lean my jetting.

So any formula's for humidity?

I have my temps and altitude charts, be nice to see were RH fits in.

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Thanks for the links, but not too much there on RH. The first link has a complicated formula for calculating RH's influence on RAD.

I have a barometer, altimeter and obviously a thermometer and a pretty good idea were I'm going with those things. I also have RH information available to me and would just like a ballpark figure of the effect on jetting. Say for instance 50% change is one main jet????? Obviously just making things up here.

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Thanks for the links, but not too much there on RH. The first link has a complicated formula for calculating RH's influence on RAD.

I have a barometer, altimeter and obviously a thermometer and a pretty good idea were I'm going with those things. I also have RH information available to me and would just like a ballpark figure of the effect on jetting. Say for instance 50% change is one main jet????? Obviously just making things up here.

The second link is probably what you want. Click on the fcr jetting chart then the RAD factor calculator at the bottom of the chart. You can use your local weather conditions or the conditions and altitude of the place you will be riding and plug in the numbers it asks for.

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The second link is probably what you want. Click on the fcr jetting chart then the RAD factor calculator at the bottom of the chart. You can use your local weather conditions or the conditions and altitude of the place you will be riding and plug in the numbers it asks for.

I missed that link at the bottom, thanks.

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I missed that link at the bottom, thanks.

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