adjusting gas/air mix on carburator

[dwk2infl]

I recently bought a small boat with a 20hp Mercury......the motor seems at least 20+ years old but had a good history. It sat up over a year with no winterization, etc. so obviously would not crank.<br />I cleaned the carb. and plugs, and I replaced some wiring and the fuel line (tank to motor). All that worked b/c it cranked last night, but I think I may need to adjust the gas/air mix on the carb.<br />My question is how will I know it's adjusted right? I know where the adjustment screw is, so do I start turning left or right?? Any help would be great - thanks.<br /><br />doug

 

[timmathis]

Re: adjusting gas/air mix on carburator

You turn them to the right to close. From lightly seated turn them out 1 & 1/4 to 1 & 1/2 turns out that should be a good starting point. Then turn each one in to it stumbles. Then out 1/2 turn do this slow when you get all carbs set. Then turn each one out 1/4 turn more. Tim

 

[Rabbitdawghunter]

Re: adjusting gas/air mix on carburator

Each model has a base setting that is measured in turns out from LIGHTLY seated. In the absence of the correct service manual I would think about 1 1/4 turns would be a good start point. If you got it to crank and idle you're probably not far off already. The way I check them is to spray premix into the throat of the carb while idling, if the engine picks up rpm the the mixture is still lean. Keep adjusting the needle out (Richer)in about 1/8 turn increments and let it stabilize for about 20 seconds. If its too rich there will be no change when you spray the premix because the carb is already using all it can handle. When the engine stalls down slightly you have it about right.

 

[Rabbitdawghunter]

Re: adjusting gas/air mix on carburator

Tim you asked a while back where central NC was. Somewhere between Raleigh and Fayetteville.

 

[timmathis]

Re: adjusting gas/air mix on carburator

Thanks Rabbit. Have you ever been to Central S.C. I have a house on Lake hartwell in Central.

 

[dwk2infl]

Re: adjusting gas/air mix on carburator

Thanks for the help...I'll give it a try