idle problems

[seastar50]

i have a 72 johnson 50hp, i can only start it in a high idle, after letting it run i turned the idle down but it only runs so long then i get a puff out of one carbs and it kicks down farther then dies, i can catch it before it idles down and it revs high and kicks down again, so u think i have a carb problem? i havent checked compression yet but it seems to have a good bit of compression, now this motor has the lever on the front of the motor to lean or rich the carb which someone has took apart, so how do i adjust the idle mixture?
thanks for any help
Jeremy

 

[fireman57]

Re: idle problems

The first thing I would do would be to check the compression before I start tearing it apart. If it is fine, somwhere around a 110 or better and within 10% of each other, then I would clean and rebuild the carbs. As far as your mixture setting when you have the carb off you can set it then. If I remember correctly the know just pulls straight off. Once you get it where you want it remove it and put it back on straight up and down.

 

[tashasdaddy]

Re: idle problems

i have the 71 50hp the carb settings are as follows, for each carb, and do them one at a time. the manual say to start at 5/8ths turns out from gently seated. then follow these directions: #1 July 2nd, 2006, 07:51 PM
OBJ
Supreme Mariner
Join Date: Dec 2002
Location: Rayland, Ohio
Posts: 10,079

Carb Needle Adjustments For Asorted Carb Variations by Joe Reeves

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(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway