1955 Johnson QD 16 won't idle

[pckeen]

I can't get this QD 16 to idle properly. Adjusting the low speed mixture knob makes minimal to no difference, no matter how rich I make it.

Any ideas? Carbs have been cleaned several times.

https://youtu.be/FHoRBF0NJVQ

 

[boobie]

Check the compression on it and then the spark. Should jump a 1/4 " open air gap on a tester.

 

[racerone]

I guess it is not a carburetor problem then !---More trouble shooting is required.

 

[F_R]

Check the synchronization between the carburetor and magneto plate. If carb is opening too soon, it will sneeze like that. Also, a crankcase seal leak can do it. Can we assume the several cleanings of the carburetor included removing the Welsh plug from the top and checking the ports below it? And can we assume the slow speed needle tip isn't twisted off?