1963 Johnson 40hp RKL 25D

DomBl

Recruit
Joined
Feb 15, 2018
Messages
5
I have been having some trouble with this motor. I rebuilt the carb and the water pump. I can get the motor started but as soon as I rev it up it will stall. It will low idle for a little bit but it’s like it misses and when it does the engine will stall. It’s not a constit knocking and it has good compression. It just seems to miss and that causes the motor to die. I also replaced the spark plugs and adjusted the set points to .02”. I would love any feed back as to what it could be. I was going to adjust the set points again to see if that helps.

Thanks for for the input
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Sneezing and stalling at idle is a sign of running too lean. Give the slow speed needle a tweak towards rich. HOWEVER you say it conks out at higher speeds also. Better revisit your carburetor job. And fuel supply. And carb linkages. Do you know how to set the carb butterfly opening and the fuel saver rod on the side of the powerhead? I'm betting not.
 

DomBl

Recruit
Joined
Feb 15, 2018
Messages
5
I have played with the needle and that didn’t make any difference. The motor would slightly rev up and down but it would still do the chug/knock until it killed the motor. I’m unsure how adjust the carb butterfly and fuel save rod. When I worked on the carb I simply took it apart and let it soak in acetone for a couple of days then replaced all the seals, needle, and float. The arc was more then a 1/4 in
 

F_R

Supreme Mariner
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Jul 7, 2006
Messages
28,195
Hoo boy, it takes a lot of typing to explain all that stuff. I've posted it in the past. Hopefully you or somebody can find it.
 

lindy46

Captain
Joined
Nov 27, 2008
Messages
3,886
Fuel pump? Try squeezing the bulb from the tank and see if it keeps running.
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,598
The automatic choke on that motor requires a working thermostat, so another reason to test or replace it. Check the spark with an adjustable tester -- plugs removed, set to 1/4-3/8 inch as mentioned. Carb cleaning may require a little more attention than soaking alone. Need to make sure every opening is clear, including the high speed jet and the nozzle running vertically in the middle.
 
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