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67 20hp Johnson runnin slow

G

GBOBBYA

New member
Motor was running fine recently and after restarting while on the water, it did not reach normal speed. Everything else seemed to work as normal. Cleaned the plugs, but nothing changed. Was able to return to the ramp at slow speed. Just got through putting in new plugs and it started up fine in a barrel, but still did not rev as high as normal. I pulled one plug wire while it was running and nothing changed......Bingo! Replaced that plug wire and removed the other and the motor shut down. Obviously, it's firing on only one cylinder. My question is; What is the most likely cause? :confused:
 
That motor has a dual ignition system.--One for each cylinder.-----Obviously one is not working.-------Pull the flywheel and inspect ignition.---------If coils have never been replaced it likely needs 2 new ones.
 
racerone said:
That motor has a dual ignition system.--One for each cylinder.-----Obviously one is not working.-------Pull the flywheel and inspect ignition.---------If coils have never been replaced it likely needs 2 new ones.
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First place to start. Bits are not expensive.

Do not think that it is a complicated thing to do. Just have a look first thing and take it from there eh?

Keep the Old Dear running.

Good luck

B
 
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I think it's a repair that I can handle. Might go ahead and replace the points while I'm in there.

She's been good to me, so I owe it to her to keep her going.

Thanks..........
 
That motor was basically the same from 57 to 77 model years.-------An excellent motor to own as spare parts both new amd used are plentiful.--------------Easy to maintain too, with no complicated electronics / wiring.
 
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