Gas spitting out of carb 50hp Johnson

[Keyboardman]

Gas is spitting out of the top carb on my 74 50hp Johnson. If I spray sea foam in the bottom carb, it wants to die out but no affect when doing the same to the top carb. Possible Reed valve problems? Great compression on both cylinders,,,,,,,,,

 

[racerone]

More detail required----will the motor run on the top cylinder ?------Do you have spark on the top cylinder ?

 

[pckeen]

Leaking carbs can often be a needle and seat problem.

 

[Keyboardman]

There is great spark on the top cyl and I've rebuilt both carbs with new floats. I pulled the intake and reed valves and the reeds look just fine. A friend of mine who works on 2 cycles (mopeds and small engines) mentioned that maybe it's an exhaust restriction? Carbon build up in the exhaust port? It was running a little better after spraying a can of sea foam though it. Advice?

 

[racerone]

Once more-----Will the motor run on the top cylinder ?

 

[Tim Frank]

How did you decide it has "great spark" on the top cylinder?

 

[emdsapmgr]

My 3-cyl looper 70 has a small fuel spit from the top carb. That's normal. It's part of the crank oiling system. Just looks odd. Maybe yours has the same feature.

 

[Keyboardman]

Not sure if the engine will run on just the top cyl. alone, I haven't tried disconnecting the plug and checked. I will do that! The spark is hot blue at 7/16" on an open air tester.

 

[racerone]

I am just going to say that it is normal for a slight amount of " spit back " on these motors.-----See it all the time.-------And yes there is an internal passage in the manifold to send oil to the top cylinder from the bottom of the crankcase.

 

[Keyboardman]

I put the intake back on after finding nothing wrong with the reed valves. The engine will not run on just one cyl alone. I pulled the top plug and it won't start, tried pulling the bottom one and same thing. It will only run, although with a miss, with both plugs attached. I've replaced the stator and the trigger checks out with an ohm meter. Maybe a problem with the power box? the coils should be good I'm thinking as they have great spark. Help!!!

 

[Keyboardman]

Bump

 

[schematic]

it is possible that the pack is firing both coils at the same time. (seen before on a different engine). Take a timing lite and check each plug wire. be sure they show 180 deg apart on the flywheel.