Briggs 20HP V-Twin Over-Heating Impacts
My White lawn tractor with Briggs 20HP model 351777 type 1036-A1 ran way too hot and chugged for 2 hours before I figured out the blower housing was clogged with grass. After clearing everything out it runs, but with less power and at what sounds like a lower RPM, so I have to cut at a much slower speed. Its been a great machine for almost 30 years and I'd like to get it back to full power. While I cleaned out the grass I adjusted the valves, replaced the air filter and replaced the plugs none of which restored the lost power. Strangely enough the engine RPM increases and runs smoother when I turn hard left, but coughs and slows down even more when I turn hard right.
Also, just after it starts there is a short "slapping" sound and excessive engine vibration, then the same thing again just after it is shut off. Starts and stops easily, but abnormal noise and shaking. No noise or shaking once it gets to full speed, just less power.
Just wondering if anyone has experienced anything similar and what I should focus on when I tear it down this winter and go through piece by piece to see if I warped a valve seat, scored the rings or burned up something else during the overheating.
Would appreciate any suggestions on where to start the diagnostic process.