1959 12hp SeaBee running rough

[budda44]

I am attempting to resurrect an old 12 hp SeaBee outboard. My research says that this outboard (model 12D18G) was manufactured by Gale in 1959. Here is what I have done so far.

1. Compression check - 80psi in both cylinders
2. Rebuilt magneto with all new coils, points (gapped to 0.020), condensors, new plugs (J6Cs gapped to 0.030), new plug wires.
3. Rebuilt carb - Soaked carb in carb cleaner and blew out all passages with carb cleaner in can. New float, new needle valve. new gaskets. Ran in high and low speed needles and then backed off 1.5 turns. I set the new float as per the directions.
4. Installed new fuel pump - fellow at outboard parts counter said that the old pump that came on the motor could not be rebuilt and said that the pump he sold me was a universal replacement for many of the smaller Johnson-Evinrude, OMC engines. It is a smaller square pump somewhat like the 18-7350 Sierra pump.

Here is the problem:

Engine cranks after about 3 pull (one choked with a little engine sputter and then motor will crank on the 1st or second pull after the choke is pushed back in. Motor runs rough and stumbles along at the start position and will run in this manner for a long period of time but promptly stumbles to a stop if the control handle is turned to the shift position. While the motor is running it smokes very badly and after 15 or so minutes in the barrel the water is very dirty and oily and smells strongly of gasoline. I am running a 25:1 gas to oil (2 cycle) mixture as per the manual.

Any suggestion as to what the problem might be or things that I might try to help diagnose my problem.

Thanks in advance for your help.

budda

 

[tmcalavy]

Re: 1959 12hp SeaBee running rough

You need to adjust your carb needles, high and low speed. The bottom needle is the high speed. Get it running in the barrel and give it some throttle with the prop in Forward. Adjust the high speed needle clockwise until it starts to cough...that's too lean. Just before this point you should find a spot where the motor runs up and smooths out...that's the sweet spot for that needle. After you get the high speed needle set, run the throttle down and adjust the slow speed needle in the same fashion. It will take longer to find it's sweet spot. My 58 Johnson 18 hp likes to run with the high speed at 3/4 turn out from seated and the slow speed at 1 and 1/4 out from seated. Yours may be different. Once you find the baseline settings, you'll need to fine tune them a little on the boat in the water. Don't run it too long in the barrel cause the prop oxygenates the water and reduces its cooling ability...it will overheat eventually and it will suck up exhaust fumes and not run as well in the barrel, too. 24:1 is the right mix for your outboard. It's normal for it to smoke a little, just a little if the water pump is working correctly. If it smokes a lot, the water pump/impeller may need to be replaced, as it may be running hotter than it should. If you can touch the water jackets when its running, it's cooling adequately....if it's too hot to touch, it's running hot. Decarbing with sea foam may be a good idea after you get it running the way you want.

 

[budda44]

Re: 1959 12hp SeaBee running rough

You need to adjust your carb needles, high and low speed. The bottom needle is the high speed. Get it running in the barrel and give it some throttle with the prop in Forward. Adjust the high speed needle clockwise until it starts to cough...that's too lean. Just before this point you should find a spot where the motor runs up and smooths out...that's the sweet spot for that needle. After you get the high speed needle set, run the throttle down and adjust the slow speed needle in the same fashion. It will take longer to find it's sweet spot. My 58 Johnson 18 hp likes to run with the high speed at 3/4 turn out from seated and the slow speed at 1 and 1/4 out from seated. Yours may be different. Once you find the baseline settings, you'll need to fine tune them a little on the boat in the water. Don't run it too long in the barrel cause the prop oxygenates the water and reduces its cooling ability...it will overheat eventually and it will suck up exhaust fumes and not run as well in the barrel, too. 24:1 is the right mix for your outboard. It's normal for it to smoke a little, just a little if the water pump is working correctly. If it smokes a lot, the water pump/impeller may need to be replaced, as it may be running hotter than it should. If you can touch the water jackets when its running, it's cooling adequately....if it's too hot to touch, it's running hot. Decarbing with sea foam may be a good idea after you get it running the way you want.

 

[budda44]

Re: 1959 12hp SeaBee running rough

You need to adjust your carb needles, high and low speed. The bottom needle is the high speed. Get it running in the barrel and give it some throttle with the prop in Forward. Adjust the high speed needle clockwise until it starts to cough...that's too lean. Just before this point you should find a spot where the motor runs up and smooths out...that's the sweet spot for that needle. After you get the high speed needle set, run the throttle down and adjust the slow speed needle in the same fashion. It will take longer to find it's sweet spot. My 58 Johnson 18 hp likes to run with the high speed at 3/4 turn out from seated and the slow speed at 1 and 1/4 out from seated. Yours may be different. Once you find the baseline settings, you'll need to fine tune them a little on the boat in the water. Don't run it too long in the barrel cause the prop oxygenates the water and reduces its cooling ability...it will overheat eventually and it will suck up exhaust fumes and not run as well in the barrel, too. 24:1 is the right mix for your outboard. It's normal for it to smoke a little, just a little if the water pump is working correctly. If it smokes a lot, the water pump/impeller may need to be replaced, as it may be running hotter than it should. If you can touch the water jackets when its running, it's cooling adequately....if it's too hot to touch, it's running hot. Decarbing with sea foam may be a good idea after you get it running the way you want.

Sorry for the above post. Just learning how to use the forum.

Thanks tmcalavy. I will give it a go. The impeller should be ok as I just changed it when I resealed the lower unit. This motor is old but has very few hours on it (probably less than 50). It has been in my dads basement for the last 25 years.