- Local time
- 8:30 AM
- Aug 10, 2022
Thats most likely the seal. It can appear to be clean around it as the oil drains down and off around it to a thin film that can be essentially invisible.Bearing on the tensioner wheel was fine.
Just tore down the engine, short of pulling the jug off. Nothing obvious. There was some carbon build-up on the piston dome and on the combustion chamber of the head so I cleaned those up. Spark plug looks good.
The only weird thing was that there was a bunch of oil in the magneto area. Weird thing was the seal and area behind the magnet was completely clean. I have no idea how the oil got there, the whole compartment was damn near spotless except for the fact there was a few oz of oil sitting in the bottom of it. No idea. It wasn't being slung around by the magnet.
And, if its really bad, could be part of the noise you hear. A few ounces would be considered bad if its been a relatively short time since you had the cover off. I had a main seal on a YZ125 go once and it sounded like a bad exhaust leak coming out the crank.