'61 Johnson 10hp RPM surge

I have a 1961 Johnson Sea Horse 10 hp that will suddenly and unexpexdedly increase rpms with no throttle input from the drive. I have no idea what could cause this. I inherited this motor from my dad, who r&r'd the ignition coils and other ignition parts, including replacement of some kind of cam connected to the throttle linkage that has something to do with ignition timing. He rebuilt the carb, too. He might have bofo'd something in doing this stuff, if so, this would be the first time I know of. He's a very mechanically inclined guy and aviation mechanic. This kinda had him stumped the last time we took the boat out and it did the rpm surging thing sporadically while underway. Engine idles okay. Sometimes has a little stumble off idle. I've kind of got a notion that might have something to do with the high rpm jet -maybe it has a piece of crud in it that my dad didn't catch when he rebuilt the carb. Otherwise, I am clueless.

T-C

I don't know anything about motors except how to break them, but welcome to the site. :mrgreen:

I'm sure someone will be along shortly to give you some advice.

welcome to site

i def would check carb easy fix ,

catfishhunter said:

welcome to site

i def would check carb easy fix ,

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