I have just aquired this motor. I went through the lower unit and worked my way up. Once to the carbs, (2) I put in a rebuild kit. The carbs seem fine. Both are jetting fuel fine. However, I seem to not be getting any power out of the top two cyl. The engine seems to idle fine, plenty of fuel going in at the carb, with plenty of suction on the carbs, and good plugs and fire. But when I take off the spark plug wires while it is running, there is no change in rpm or smoothness of idle. The engine revs up quickly and returns to idle without dying. Is this normal for this engine? I do know of auto engines that do this for conservation of fuel.
<br />These engines will sometimes run poorly, but run, on less than all cylinders.<br />I would double check the spark, using a spark tester with an adjustable gap. Reason being, these ignition systems are capable of throwing one heck of an arc, and yet, when a component fails, have enough potential to 'zap' ya.<br />My gut feeling is the switchbox or one of the four coils is defective...but especially the switchbox, as it is rare to loose 2 coils simultaneously (you stated you have 2 lazy cylinders).