Top cylinder not hitting

Arug.....I give up and must ask for help


I have a 1985 25hp 2 stroke Johnson that is not hitting/not working on the top cylinder


Checked:/completed


92lbs compression both cylinders
Nice blue spark both cylinders
Tried moving exciter wire and high tension spark wire from bottom cylinder to top. (Just to double check the coils) no change
Carberurator cleaned and rebuilt
Tried taping wood dowel on power head in area of reed valves
New spark plugs. Top plug (new) seems dry, not covered with oil and gas


What the engine will do is run on the bottom cylinder only


And I am out of ideas, engine should have fuel, spark, compression, So why has the top cylinder dropped out?


Any one with any ideas?

Thanks

If tapping the dowel was supposed to "unstick" a reed valve, 'tain't going to happen. Reeds don't stick. But they do break or get a foreign object lodged under one. Both are very rare, but possible.

When the top piston is in downward mode... Does the crankcase pressure escape (blow out) of the carburetor throat? If so, a broken leaf valve exists.

What make, type, spark plugs are you using... set at what gap?

The spark must jump a 7/16" "air gap" with a strong blue lightning like flame... a real SNAP! Does it?

92 psi exactly on both cylinders? If so, a possibility exists that the center portion of the head gasket may be faulty resulting in a crossover condition.

Any water droplets showing up in either cylinder... on the plug electrodes? Under certain conditions, especially with salt water, those droplets will show up, not as water, but a extremely small BB's welded to the spark plug electrodes.