18hp evinrude bad cough

[JPsanta]

hi guys , have a 1966 18 hp evinrude , seems not to run to bad butt has a bad cough at low speed , but new carb kit in it , checked plugs when got home , top plug was very black , bottom was clean , any ideas

 

[Crosbyman]

check compression
recheck carb ... blow out ALL passages with carb cleaner incl. side channel to upper LS needle check under #25

 

[racerone]

Sounds like it is running on 1 cylinder.----Help yourself and post compression numbers.----See if spark jumps a gap of 1/4" or more on a simple test device.----Check fuel pump diaphragm,----Check thermostat as they are often missing or stuck open.----Open low speed mixture needle to get rid of lean sneeze.

 

[JPsanta]

pretty sure compression was 120 on both cylinders