Hi David, It does sound like it's running lean on the high end. The solution is likely to be related to a fuel flow problem like a clogged carburetor jet or obstruction / air leak / weak point in the fuel delivery system such as a clogged filter / fuel pickup / regulator / missing gasket / dried-up diaphragm, etc.
A constructed flow problem won't manifest itself on the low end as the engine only needs a trickle of fuel to idle correctly, however when you open the throttle the trickle has to turn into a stream... Filters and hoses are easy and cheap / carburetor rebuild kits with diaphragms and gaskets cost about 15-20 bucks and take about 30 minutes to install. Good luck! -Francois 1990 34+ "Take Five" Josh and Chuck, Mixture is new with AV gas so no issues there. Only one adjustment screw on carb. Seems to only affect low throttle. As said all good in neutral and good up until ? throttle in gear. Chuck mentioned if spark plug grey and chalky, which it is, it is running lean at top end. How does one adjust top end without adjustment screw. Thanks in advance. David F. Risch (401) 419-4650
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