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Carb adjustment b71 50hp Evinrude

  • Thread starter Kent Bloomquist
  • Start date
K

Kent Bloomquist

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" So far on this engine, I hav

" So far on this engine, I have replaced thermostat and get a running temp of about 140, replaced spark plugs, replaced fuel lines and bulbs, removed lean/rich linkage on idle screws per mechanics suggestion. Adjusted carb/timing sync and carb/carb sync per manual. Ran a bottle of OMC fuel system cleaner. Set idle screws out 5/8 turn per manual. Engine idles, but I get a slight flow of raw fuel out the throats of the carbs at idle, enough to drip off of bottom of air silencer housing maybe every ten seconds or so. Hadn't noticed before, because always had silencer cover on. "
 
"Kent.... The proper carb adju

"Kent.... The proper carb adjustments are as follows. After the initial turn out setting, do one carb before adjusting the other.

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

Joe
"
 
" I did the adjustment as you

" I did the adjustment as you describe, but still have fuel slowly flowing out of the throat of at least the top carb, can't tell if the bottom one is too or if it is all from the top one. Float problem? or what do you suggest I do.

Thanks, Kent "
 
"Kent.... Carburetors flood wh

"Kent.... Carburetors flood when either the float needle valve is worn or the float is out of adjustment.

If the tip of the float nedle valve is worn, replace the needle valve assy (needle, seat, and washer).

When holding the carburetor upside down and viewing the float from the side, the free end of the float should be ever so slightly higher than the hinge pin end.. When viewing it from the end, it should not be cocked.

Joe
"
 
" Buy rebuild kits,and a can o

" Buy rebuild kits,and a can of carb/choke cleaner from your local John/Rude dealer clean and rebuild carbs as per your service manual.3/4 turns open on low speed/idle mixture needle.Very simple carbs just follow your service manuals instructions "
 
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