Re: '62 40 hp johnson maiden voyage issues
Just my 2 cents worth, I own a 1960 RDS-22 that should be pretty close to what you have, it too is a 40 horse Johnson, and boy have I learned ALOT about this motor....First of all, I agree, try running it with the fuel cap off, that should remedy the "negative pressure" possibility.
2 things have to happen at full throttle..The butterfly in the carb has to go fully open, and against it's stop, and the "timing plate" must also go it's full travel and be against it's stop. Both of these conditions are dependant on the vertical rod that is operated by the throttle linkage, the one with the 2 mercury switches on it. These components gave me fits on my motor, until I finally got the flywheel off by "renting" a puller from Advance autoparts, then, it was really easy. The vertical shaft, or rod, can't have any play in it, but cant be too hard to rotate either...There's a shim underneath the strip that holds it in place. One of the 2 screws that held the actuating bracket to the timing plate was gone, and the other hanging in with one or two threads. Once they were replaced, (with locktite) my timing plate was glad to go to its stop, as well at the butterfly on the carb at full throttle. Then, after re-assembling with all new ignition parts, it was off to Allatoona. Stupid battery too weak to spin her over, so I grabbed the pull rope with the choke in the "auto" position, and she purred like a kitten on the first pull. You can also simply pull out the rope until the compression release engages, then hit the starter, and she starts fine, when your battery is weak. Went to full throttle on the lake, and MAN....HOLD ONTO YOUR HAT...She's a Screamer!!! Im getting about 40 mph now, and very happy with this antique...Im thinkin your motor is alot like mine, and mine was doing the same as yours before I did all of this....If your motor is different than a RDS-22....Nevermind
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