You can make some observations. After running the engine, shut if off and check the plugs. Do they all look the same? After idle, they should all be black and oily. All crossflows run overfueled at idle. That's normal. If any plugs are dry looking, that's suspect. During any carb overhaul, pull the jets out of the carb and check for debris in the orfice. Esp pay attention to any carb throat that feeds a spark plug that looks abnormal/dry. Debris can starve an cylinder. And will cause that cylinder to be under lubricated with oil-not a good thing. You can also do a high rpm throttle chop (shut the engine off abruptly at high rpm's.) Compare all of the 4 spark plugs. At high rpm's the plugs should be dry and light tan in color. These two shut off procedures are a good test, as the high rpm chop shows what is going on with the main jets, the idle shut off shows the idle jet.
