Johnson 55EL78 Carb question

[Bryan Dover]

" My engine would'nt idle

" My engine would'nt idle and was hard to start, I cleaned out both carbs and adjusted the floats and now it starts and runs. It seems to idle a little rough, in my opinion. I'm not sure how smooth this engine is suppose to idle. I adjusted the ignition timing to 3* advance at idle. I checked the compression on both cylinders, 140/130. Replaced all the fuel lines, disassembled the fuel pump, the diaphram is ok. Set the floats at 1/16" as measured from carb flange as per service manual. The only thing I found that worries me is the low speed idle jet in the lower carb. When I took the plug out the head of the jet fell out, like it had been over torqued. It was just the head of the jet, the part the screw driver goes on, the rest of the jet is still in the carb. The remaing part of the jet appears to be clean, as viewed with a flashlight. Should I be concerned with this? Will the remaining jet still meter the fuel at idle?
Thanks in advance, Bryan "

 

[joereeves]

"Bryan.... The threaded portio

"Bryan.... The threaded portion of the jet that's still in the carburetor is the portion that would contain the metering hole unless more than just the head broke off. That portion should meter the fuel normally, BUT the question arises... is it secure (tight), or will it viberate out?

The engine should idle fairly smooth but of course not as smooth as say a 3hp might idle. Possibly the carbs are slightly out of synchronization or are opening a little too soon. The throttle should just start to open when the scribe mark on the cam aligns dead center with the carburetor throttle roller.

Joe

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