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Carburetor Adjustment

J

Joseph Czech

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" I was wondering if someone c

" I was wondering if someone could post step by step instructions for synching and adjusting carbs. I for instance have a 1996 Tohatsu M70B which is a 3 cylinder. I would assume that this carb procedure would be pretty universal.

Thanks,

Joe "
 
"Joe,

The procedure is basi


"Joe,

The procedure is basically the same for just about all outboards.

First look into the carb bores and make sure the throttle plates are opening and closing in unison. If they are not you have to adjust the linkage that joins the throttle shafts.

You probably have a screw which sets the low speed mixture on each carb. These should be set equally. Screw them in until yuou feel the needle lightly contact the seat. Back them out 1 1/2 turns each.

The engine should idle with the throttle plates closed. If the idle seems too low or high, you have to adjust it by advancing or retarding the timing. The timing is determined by the position of the sensor or trigger coil which is under the flywheel. It is moved by the throttle mechanism. Generally there will be an adjustment screw which determines the position at idle. It is best to set this with the link to the carbs disconnected. This way the throttle plates on the carbs wil remain closed as you set the timing at idle. You may have to adjust the link so that the carbs remain closed at idle.

You can try leaning the idle mixture screws by 1/8 turn each. If the idle seems smoother or faster when you do this, you can try another 1/8 turn on each screw. If you go too far with this the idle will get rough, and the engine will cough and maybe even stall. If this happens reverse the procedure until things seem okay.

When you get the idle right, connect the link to the carbs. As a rule the throttle plates should start to open after the timing has begun to advance. At full throttle the throttle plates should be almost horizontal.

"
 
Thank you very much. That is

Thank you very much. That is a well written very understandable response. I will do this procedure this weekend.
 
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