Carb question that is bugging the hell out of me!

[rhillman75]

I am a fuel injected guy! The only thing I own that is carb related is a weed whacker and a push lawn mower. I have a 40 HP Mariner Jet 30 3cyl 2 stroke. I just got the carbs rebuilt and I have a question about the settings. I know the factory is 1 1/4 out from seat. Should ALL the carbs be adjusted EXACTLY the same when the motor has been submerged? I noticed if I have ALL 3 carbs backed out at 1 1/2 turns it starts in a milli-second without hardly pushing the choke. But when I put it in forward or reverse it tends to grind the gear a little. Is this common? I also notice a REAL rich gas smell while it idles. If I turn in the screws back to 1 1/4 from seat... it is HARDER to start and idle unless it has been running about half an hour. So my question is..."should they ALL be adjusted equally or differently?"

 

[latin monkey]

Re: Carb question that is bugging the hell out of me!

running it a little rich is alot better than running it lean. at 1 1/4 out its harder to start because its set too lean. you have to adjust them when you have it on the water under a load. do each carb one at a time, leave settings you have now at 1 1/2, when on the water with it warmed up turn screw out (counter clockwise) until it starts to run like crap then turn screw in until it sounds like all cylinders are firing and its running better, then leave it and on to the next one

 

[CharlieB]

Re: Carb question that is bugging the hell out of me!

The weed wacker and the outboard are basically the same critter, neither has an accelerator pump and rely on the idle mixture being 'just' fat enough to provide the additional fuel necessary for acceleration without being so fat as to foul the spark plug.

Float heights are critical, all must be adjusted the same and by the factory service manual.

1 1/2 turns out is only a starting point, final adjustment of idle mixture must be done while on the water under load.

With the jet, load is always there, propped motors must be in Forward gear.

With the engine at normal temp, adjust each carb to best idle speed, then go back and further richen each idle mixture screw an additional 1/8 turn.

Test by slamming the throttle wide open, any lean miss, cough, or hesitation, then further richen the mixtures just the blade width of the screwdriver slot.

Repeat acceleration test until perfection.

Readjust idle speed with idle timing adjustment.