Carb Adjust Revisit? Evinrude 4 hp (1983)

[Intermediate Mariner]

Good Morning,

I guess I am just cursed b/c I can never get my motors running smooth. My last motor was an old Lark 40hp and I rebuilt the whole thing and it never ran right... now I am working on a 1983 Evinrude 4hp (M# E4BRHCTA); I just can't seem to find that "sweet spot".. it keeps jerking around like a Hawaiian Hula Dancer!

Rebuilt the fuel pump, carb, did points, head and exhaust gaskets, plugs, hoses, all the good stuff. It's one pull start but I just can't get it smooth. Also did water pump, it's flowing good water and fuel bulb is tight.

I am seeing conflicting info out there on adjusting the idle..

Joe Reeves did a post here that said this:
"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."

I also am looking at a 1971-1989 J/E manual that says:

"Set the idle mixture screw at the specified number of turns open from a lightly seated position. In most cases this is from 1 to 1-1/2 turns open from close.

Start the engine and allow it to warm to operating temperature.

With the engine running in forward gear, slowly turn the idle mixture screw COUNTERCLOCKWISE until the affected cylinders start to load up or fire unevenly, due to an over-rich mixture. Slowly turn the idle mixture screw CLOCKWISE until the cylinders fire evenly and engine rpm increases. Continue to slowly turn the screw CLOCKWISE until too lean a mixture is obtained and the rpms fall off and the engine begins to misfire. Now, set the idle mixture screw one-quarter (1/4) turn out (counterclockwise) from the lean-out position. This adjustment will result in an approximate true setting."

So do you turn it in or out after the initial setting? And what's the best initial setting?? My mechanic says one turn, books says 1 to 1-1/2", others say 1-1/2, I also actually seen 3/4 turn in another book (but it was from '65-'78 but should be the same)! And which is it for the adjustments, 1/8 or 1/4??

Do you have it in gear the whole time? Do you keep lowering the throttle? What if it dies, do you have to start over since you'll have to increase the throttle to restart??

Out of curiosity, what's the neighborhood of the final setting? One turn, two turns?? Doesn't seem like much leeway with adjusting between 1/8 & 1/4 turns at a time! This is very frustrating wow!

Any help greatly appreciated.

Thanks Much

Shawn T
Wichita

 

[oldcatamount]

Re: Carb Adjust Revisit? Evinrude 4 hp (1983)

Yup, lots of conflicting info and it's because even though all motors a basically the same, there's no two alike. Here's my input, close the low speed needle valve clockwise until it seats, now turn it counterclockwise at least one full turn. Start the motor and let it run for a couple of minutes. After it's warmed up, in neutral, play with the needle valve. Turn it clockwise (lean) in 1/8th increments and give the motor a few seconds to react each time you do that. You'll get to a point where the motor will cough (lean sneeze). Stop turning the needle clockwise and go counterclockwise 1/8th turn and see if you like it there. You may need to do this a couple of times before you find the best setting. Be patient, if the timings correct and all other ignition components are correct. you will find the smoothest idle setting. Put it in forward gear and see how it reacts to the throttle. Tweek it to fit your needs.

 

[Intermediate Mariner]

Re: Carb Adjust Revisit? Evinrude 4 hp (1983)

Thank Much oldcat, appreciate the input!

I will try that... as you have indicated it seems that just playin with it and finding the best spot is the way to go. After playing with it yesterday I ended up with a setting that in the end is only 1/2 turn out, would that seem too lean?

Also you mentioned timing, which has been foggy for me. Does this little 4hp have a timing adjustment?? Another problem I am having is that it is sort of "herky jerky" - don't know how else to put it other than this: it runs good then jumps a little, possibly like a surge so to speak (a definite brief intermittent fluctuation in throttle).

Thanks