I am working on a buddies engine. It's a 1985 Johnson 115hp, model J115TLCOS. This engine had been sitting for 2 or 3 years. He brought it to me for a tune up. I rebuilt both carbs, replaced the water pump, lower unit oil, and the spark plugs. It had a bad power pack, so I replaced that too. The engine has good compression in all cylinders. He took it out on the lake last weekend for its first run. He said when it runs over 3000 RPM, it sounds and feels like he hits a log every minute or so. Sounded like it was jumping out of gear. I checked the linkage, and it appeared to be adjusted correctly. I pulled the lower unit and drained the oil, no chunks or anything. I pulled the gears and they look fine. Other than normal wear, the gears look good. I have no idea what it could be. I'm open for suggestions or input. Thanks.
