40 hp Johnson 1964

[beach]

Took out tonight for the first time since purchase and major tune up. Tops out at 2800 rpm and pushes the boat about 10 mph.<br /><br />Boat 17 ft fiberglass<br />Gas 97 Oct<br />Oil 32:1<br />Prop 10 1/2 x 12<br />60 ft above sea level<br />125 psi both cyl.<br /><br />What should I look at 1st?

 

[JB]

Re: 40 hp Johnson 1964

Hi, Beach.<br /><br />Is the throttle butterfly opening fully?<br /><br />Is the throttle linkage advancing the ignition fully?<br /><br />Are both cylinders making power? This is the most likely problem. By disabling each cylinder (remove plug wire or short the plug out) you can determine this. If the engine dies with one disabled but ignores the other being disabled, the cylinder it ignores is not making power.<br /><br />Check dead cylinder for hot, blue or white spark at least 7/16".<br /><br />Got spark? Squirt some fuel premix into the carb for the dead cylinder. Speed up? Overhaul the carb.<br /><br />Let us know what you find.<br /><br />Good luck.

 

[beach]

Re: 40 hp Johnson 1964

Lower cylinder no spark.<br />Traced problem to ignition switch.<br />Was getting ground at switch in on position.<br />Will take out tomorrow should run alot faster.<br /><br />What can I hook the tach lead up to?<br /><br />Thanks for your help JB

 

[beach]

Re: 40 hp Johnson 1964

Now the motor wont idle without opening the butterfly a little (not the choke). Adjusting the low speed mix has no effect. High speed is not adjustable. Could the motor be flooding out from the carb? It doesnt run above 3000 rpm seems to have trouble doing that. It actually ran smoother on just the top cylinder if that indicates anything. When I can get it to idle it runs real rough, bumps. Am rebuilding the carbs today, anything else I should be looking at.

 

[DJ]

Re: 40 hp Johnson 1964

You're on the right track. Let us know.

 

[beach]

Re: 40 hp Johnson 1964

Disassembled carb, everything looked good except the float, looks like cork, really bad shape. Where can I get a new float, my carb kit didn't include one. I also need a new housing for the heat choke (housing is cracked where the compression fitting is) and new electric choke.<br /><br />Have type 2 carb with heat/electric choke.

 

[DJ]

Re: 40 hp Johnson 1964

beach,<br /><br />The float should be available at your local John/Rude dealer, same for the other part.<br /><br />If not, try here.<br /><br />www.twincityoutboard.com<br /><br />The cork ones would go bad after a while. The new ones are a different material.

 

[beach]

Re: 40 hp Johnson 1964

Would a bad float cause the problems I've experienced? In WOT the motor seemed really bogged down, and when it would idle it was really rough. It was acting like intermitent spark but I don't know if that possible with this type of ignition system. I've replaced both coils, pts, condenser, wires and boots. When I ck for spark it's always there.

 

[rickdb1boat]

Re: 40 hp Johnson 1964

Then it could only be a compression problem or fuel problem. You've already ruled out bad spark. Check the compression. If that's OK, then head to the carb. Make real sure you have spark under a load and not just in a tank or on the muffs. You can use a timing light to do this the next time you run it, to see if a cylinder is dropping out under load on the water. But check the compression first..