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40 hp mariner carb jets

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dreemon

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"just wondering at what rpm do

"just wondering at what rpm does the low speed jets work up to and appox when do the high speed jets start to take over, 91 40hp mariner, thanks"
 
"Johnny, the low speed jet con

"Johnny, the low speed jet controlls the ratio of gas/oil to air when the engine is at idle or low speed. At higher speeds both jets are in fact contributing to providing the correct balance.

I can't find any documentation as to what rpm, or vaccum pressure ect is the "cross over point" where the high speed jets function becomes apparent. It is all relative though to the amount of fuel being pumped into and sucked through the carb into the crankcase."
 
"thanks Graham, just wondering

"thanks Graham, just wondering if I could set the low idle jets back as far as possible so motor wont run as lean, see how it goes backed out 3 full turns, and just run it at lower speeds, Thanks again."
 
"about 1000rpm, you can find o

"about 1000rpm, you can find out by running on the water at 1000rpm and adjusting the low speed jet, if you adjust it and no change in engine you are above the range of the low jet. The engine should not run lean when properly adjusted unless something else is wrong."
 
"Johnny, I agree with JB, from

"Johnny, I agree with JB, from "seated" your low speed jet should only need to be about 1 1/2 turns out, +/- maybe an 1/8th of a turn. If it's leaning out on you, you may have an air leak somewhere...."
 
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