Small Engines (Lawn Mowers, etc.): motor loss of power, combustion chambers, grass problem

Question
ben, i have john deere 260 riding mower 46inch 3 blade 17hp 1cly kawasaki engine eng# fc540v, ser m260t011632. the engine lost power. will start and run. seems to have a higher max running rpm, but when engage blades, or let clutch out to start pulling, engine rpm's drop low, almost to idle and will barely pull hills or cut high grass. problem started out of the blue. i clean air filter, still same. after engine hot i ran compression test and have 90lbs compression dry, wet with 3 squirts oil i have 125. the engine does not use oil and oil is clean. the engine sounds
more noisey to me than normal, but not a rod noise. the mower is a 1992 model i beleive. the exhaust output seems normal and not restricted. i believe the choke plate is open and not closed but i will check to make sure. it has stucked closed before and skpis and sputters and black smoke when that happens. motor seems to be running like normal ignition
i wonder if the compression ring has broken? also i wonder if i am getting enough fuel? someone suggested i may have
restricted fuel inlet or weak fuel pump. fuel filter is
orignal. i will change filter. i'm not sure but the engine may have some type mechanical governor, poss problem? any help would be appreciated thank you gary

Answer
First off 90psi compression is much too low, especially when hot, compression is lowest when the engine is cold and parts have contracted. You could have a few problems. Might be bad valves, worn or broken ring or rings. But I would believe with a broken ring you'd be pushing some smoke as it passes by the ring. These are tough fixes for the home repair man. Problems of this type need to be tested using professional equipment, like a engine leak down tester, to test the combustion chambers integrity. The 3 squirts of oil, simulate a good set of rings, and cylinder wall. ........Tom