I recently took into inventory a 1975 Briggs 3 HP Model 80202. Before I even tried running it or disassembling it for a rebuild I first do a compression test and (now) a cylinder leak down test. Compression was at 100PSI and the leak down test was within specs and acceptable. I then take off the head and inspect the bore. I noticed that there was a LOT of carbon buildup on top of the piston, on the underside of the cylinder head and on top of the deck around the valves. After cleaning all the carbon off I installed a new head gasket and put it back together and rechecked the compression and cylinder leak down. The compression was now at (only) 85PSI,
but the leak down test remained the same. I thought that the initial compression test result of 100PSI seemed quite high, as my experience with these engines is that even on a rebuilt engine it typically runs at about 90-95 PSI max. 85PSI is certainly not bad at all or otherwise a "deal breaker", but it did surprise me. Finally, I did try running the engine and it started, idled, and ran fairly well. Your thoughts?Michael
