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motor coughs at low idle speeds

That is usually an indication of lean condition on one or more carburetors.------Do you leave fuel in the carburetors for long periods of time and over the " off season " by any chance ?
 
Can't make paragraphs,sorry.The carb/s probably need cleaning and adjusted. The low speed air/fuel screw needs adjusting.There is a screw on the side of the carb.It has a spring on the shank of the screw. Try turning them out 1/8 of a turn, wait 10 seconds then another 10 seconds. This will increase the amount of air mixed with the fuel. To adjust the whole system.Do this for all the carbs. Turning the screws in at 1/8th at a time until the motor bucks,stalls,kicks then turn out 1/2 time. Do this for all 4 and clean the plugs or replace.This will help as dirty plugs don't spark as well.
 
Jerryjerry05 said:
Can't make paragraphs,sorry.The carb/s probably need cleaning and adjusted. The low speed air/fuel screw needs adjusting.There is a screw on the side of the carb.It has a spring on the shank of the screw. Try turning them out 1/8 of a turn, wait 10 seconds then another 10 seconds. This will increase the amount of air mixed with the fuel. To adjust the whole system.Do this for all the carbs. Turning the screws in at 1/8th at a time until the motor bucks,stalls,kicks then turn out 1/2 time. Do this for all 4 and clean the plugs or replace.This will help as dirty plugs don't spark as well.
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What is ideal fuel/air mixture ? How do i sync and link each carbs ?
 
You probably have gummed carbs caused by stale fuel. I would assume this before messing with any adjustments on the carbs. You dont want to throw them out of balance. This would explain the stumbling at idle rpm (low speed jet is clogged) but fine running at high rpm (high speed jet is fine). I had this problem on my 50hp.
 
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