1966 johnson 40 hp bucking @ 1/2 throttle

[sschaefer877]

Hi all, Need some new ideas. I have a 1966 johnson 40 hp (rdsl-28b) that is bucking @ 1\2 throttle. I have replaced points, wires, plugs, rebuilt carb, removed power head to inspect bell crank (seems o.k.). I have tested the spark with a spark lite tool ( looks nice and strong) but still have a problem. I installed while re-building carb a new low-speed needle valve. I cannot achive max idle @ 1 1/2 turns out as book says but only 1/4 turn out. @ 1/4 turn out engine really bucks. I have inspected the reeds ( look good ). I like this forum I have tried many ideas from other posters.p.s. new gas tank and gas line. I also checked the cut out switch. i'm stuck need help!.

[Paul Moir]

Welcome to Iboats!When you rebuilt the carb, did you place a new gasket over the high speed nozzle? That is, between the end of the high speed nozzle and the bottom of the carb bowl? It looks like a thick washer.You ought to end up somewhere around 3/4 - 1 and 1/4 out on the low speed.

[sschaefer877]

Hi Paul,I did replace the the gasket. I do buck less when I set the low speed needle valve 1 1/2 turns out but i idles better @ 1/4 turn out. Thanks for your quick response

[sschaefer877]

any one?

[sschaefer877]

SAT. I WILL REPLACE THE TOP SEAL. SEEMS A LITTLE WET BUT NOT MUCH. MY REPAIR MANUAL SHOWS A SPECIAL SEAL PULLER. IS THIS A SPECIAL SEAL PULLER BY OMC?

[sschaefer877]

Sorry about the caps. I'm not a good boat mechanic or a good typer!