View Full Version : WH Carbs idle jetchange results
coffeeguy
08-12-2025, 06:16 AM
I am not sure if richening or leaning the idle jet(s) also has an effect on the overall air/fuel ratio through all throtle positions. If I went smaller on the idle jet do I wan to go a little more on the main(s) to keep the same final a/f ratio?
rjdubiel
08-12-2025, 07:47 AM
once you open the throttle plates those are not getting used much. You want to go bigger on idle jets to lean out idle, bigger is more air, leaner idle fuel mix. Depending on how lean you go on the main and what motor you are running on what boat you are running, all factors, be careful running half throttle as these are 2 circuit carbs and if you go lean on the main jets you will have a lean spot in the midrange rpm.
coffeeguy
08-13-2025, 06:22 AM
My previous thinking was in reverse thinking in reverse . I am thinking I will increase the idle jets (from 42 to 46,wh 15 carb) to lean it out a little at idle and increasing the mains to compensate for that on top end(72-74 and 74-76). The motor has always fat (89 block,7 pedal front and 33cc heads nothing else).
tlwjkw
08-13-2025, 12:46 PM
idle and mains have absolutely nothin' ta do with each other.. idle circuit is zactly what it says... idle jets increase or decrease air only.. once you move tha throttle a smedin' tha idle circuit goes away............
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