Lean <–> Rich adjustment question

[SnappingTurtle]

1981 Evinrude 6HP

I bought this motor recently and it seems to run well, but I have not had a chance to test it in the wild (boat is not finished yet, but getting closer). So up to now all short test have been done in a drum.

My naive question.

Lean <–> Rich adjustment.

How do I know it set is OK?

There is no stop when turning it. It can be screwed all the way in, or completely unscrewed from the carburetor.

Is there a magic formula to setting it before fine tuning adjustments are made, i.e. all the way in and then three turns out, or something like this?

I would really hate to run it too lean & seize the motor, and it being new to me I am not sure the basic setting is right.

P.S. I know I need to buy a manual, but it is a Made in Belgium, and I haven't found one yet. The Stateside models/manuals are only for either 4hp & 7.5hp for 1981, and mine is a 6hp.

Thanks!

 

[SnappingTurtle]

Re: Lean <–> Rich adjustment question

sorry wanted to upload a photo

 

[Joe Reeves]

Re: Lean <–> Rich adjustment question

(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 1: 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.

Note 2: If the engine should be a three (3) cylinder engine with three (3) carburetors, start the adjustment sequence with the center carburetor.

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.

 

[SnappingTurtle]

Re: Lean <–> Rich adjustment question

Photo

 

[SnappingTurtle]

Re: Lean <–> Rich adjustment question

(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 1: 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.

Note 2: If the engine should be a three (3) cylinder engine with three (3) carburetors, start the adjustment sequence with the center carburetor.

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.

Thanks JR. That is something even I can grasp!

I'll sleep better now.

 

[paulrfrancisco]

Re: Lean <?> Rich adjustment question

Re: Lean <?> Rich adjustment question

Can anyone tell me if this holds true with the 4.5 hp evinrude 1980?

 

[tashasdaddy]

Re: Lean <?> Rich adjustment question

Re: Lean <?> Rich adjustment question

these hold true, until you get to the both fixed jet motors. the above is an exert from Joes original post.
http://forums.iboats.com/showthread.php?t=167352

 

[Xcusme]

Re: Lean <?> Rich adjustment question

Re: Lean <?> Rich adjustment question

Paul, Yes...you have a single needle valve (slow speed). No adjustment for the high speed mixture, it's a fixed jet.