Johnson Seahorse 20hp

[roberto]

Could anyone advise how I can solve a persistent popping on this old pre-throu prop engine. The mixture screw needs to be wound out a long way before the engine will think of running properly but will then misfire in bursts. I have changed the coils and am sure it is not coils, leads or plugs, points etc. I suspected the inlet valves -but the petals seem clean and ok. Plugs run very black. One suggestion is that the seals have gone. Could this be the problem? -Rob.

 

[JB]

Re: Johnson Seahorse 20hp

Howdy, Roberton.<br /><br />From your description, I would overhaul the carb with special attention to getting all of those tiny passages cleaned out.<br /><br />You will need a manual. It will be a lot less than paying someone else to do it, and you will have it done when you want it, not the second tuesday of next month.<br /><br />While you are working on it, you should do the fuel pump, too, and check compression.<br /><br />Good luck.