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Old 07-15-2013, 04:36 PM
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Rich88 Rich88 is offline
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Join Date: Nov 20, 2008
Location: Wilds of Ellington, CT
Posts: 4,182
Originally Posted by Frank
Looking for carb adjustments to provide better mileage for Sluggo. I rebuilt the carb (MC4150) a few months ago and it ran, but poorly. My mechanic sent out out to a carb guy he knows who corrected my freshman errors. Got it back and it ran fine and still does but I'm down to 7MPG .

I know I can do better and it did before my attempt to rebuilt the carb. I used to enjoy 11-12mpg. The thing runs fine but I'm going to admit my newbie-ness and plead for guidance on what to turn, when to turn it and which way to turn it.



Don't know if you really meant MC4150 or the stock MC2150. Either way, the only adjustments are choke, idle mixture & idle speed. If those are correct there are no more tweaking adjustments, and none of those will affect the mileage anyway. The only remaining factors affecting mileage is whether the power valve is leaking by or not, and the jet size. Too big = rich mixture.

Power valve leakage can be confirmed by pulling the vacuum line from the PV vacuum port to see if any gas comes out. Gas = leakage = poor MPG. No gas is good and put the hose back.

Further, you should check the plugs. Proper mixture should show light tan plugs. Brown or black = rich mixture.
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