I have a B&S I/C engine model 126802-3154-01 on the MTD mower. The carb has a idle mixture screw. Last winter I cleaned the carb. I adjusted the idle mixture screw according to what the B&S help link says i.e. at idle 1200 rpm turn it counter-clockwise till engine slows down, note the position, turn it clockwise till engine rpm falls again and then set it to the middle of the two settings noted. So far so good. Engine runs OK and throttles good but the spark plug ground strap and the porcelain around the electrode is generally black and wet with fuel. I have tried to lean it out a little and the wetness goes away but I am afraid that I may be leaning it out too much. I have the same engine on my pressure washer and I had cleaned the carb on that too; the spark plug on the washer is nice tan in color. Is there something else that I may be missing on the mower engine?

TIA
Paul

Make sure the air filter on your mower is clean. The adjustment is for the low speed and does not affect the high speed operation much. You cannot lean it out so much that it will damage the engine. You may never get the plug to look like the one in your pressure washer which is run under a fairly constant load, and usually never at an idle speed. As long as your not having problems with spark plugs fouling, you should be alright with your mower.

Thanks a lot 30year!!
The air filter is new. I changed it just last month.

Paul

Little update: There is a wire-mesh foam filter before the real filter. It didn't look dirty but must have been because by removing it the engine seems to run just right i.e not rich. The spark plug is now dry. Not quite golden yet but almost there. Thanks again for your help.

Paul