1998 Mercury 25HP two stroke, manual tiller, manual start. Symptom(s); She is dropping her bottom cylinder at idle to 1/4 throttle rpms. She will pick-up her bottom cylinder when advancing the throttle above 1/4 rpms and run fine. When decreasing the throttle, she will drop her bottom cylinder and stall. She is very nasty getting restarted. NOW THEN ……… if I bypass the idle speed limiter and open the throttle, she’ll start and run on both cylinders UNTIL I DECREASE THROTTLE at which time she’ll drop that bottom cylinder and stall again. Up until recently, this motor has run like the Energizer bunny. I’ve done everything to this motor EXCEPT tearing her down to inspect rings, connecting rods, pistons, and the cylinder walls UNDER the rings. Could it be possible that the cylinder wall below the rings (on the bottom cylinder) is damaged so as NOT to create enough vacuum to pull the gas/oil vapor from the reed valves into the combustion chamber at lower RPMs ?????
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