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Mercury main jets-elevation

T

Traction

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Does a mercury outboard require a main jet change when changing elevation, moving from 3000 ft to 6800 ft. I have a 2003 xr6 150. Runs great, just want it to run great at 6800ft. I know that I will have to change props with the power loss, but unsure about the main jets. Thanks, Tom
 
If you're not going to stay at that elevation, all I'd do is run less pitch on the prop. The carbs need to lean them out a bit, but the hassle is not worth it if its a temporary thing.

YOU and your motors (boat, car, truck, etc.) will all be wheezing at that altitude!

Jeff
 
The Mercury service manual has the information ( I have some online )----------A comprehensive chart to tell you to go from the size you have to what you need.-----Different size for every 1000' change.
 
Not sure why you can't find them ------------Google for manuals -----------Takes about 27 and half seconds to find them.
 
I know this is an OLD thread, but I have a related question. I found the high altitude jetting chart in my service manual for a '96 Mercury 125hp. It has suggested sizes for various altitudes. My motor is going from near sea level to 8800' where it will be used almost exclusively from now on. I know the carbs need smaller jets, and prop needs less pitch. I'm a bit confused on how to read this jet chart. It says factory jets are usually ok up to about 5000', but after that they should be reduced according to the chart. So the chart gives the factory jet size, and what it should be reduced to for every 1000' of elevation gain. My question is, is that chart for every 1000' above 5000', or every 1000' above sea level? If I read it the first way (every 1000' above 5000) then my jets would go down from the stock sizes .070,.080,.078,.082 to .068,.076,.074,.078. But if I read it the second way (every 1000' above sea level) then the jets would drop further to .064,.072,.070,.074. Which one is correct?
 
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