Oil seal failure

[ecefour]

I've put about 3,500 miles on my Twinstar this season. It's been dependable but finally broke down for the first time.


This afternoon I got about a mile from my house before my rear tire started losing traction. That's when I realized the bike was pouring oil everywhere. I turned off the engine and walked it home. Thankfully I shut it down before the sump ran dry.


When I got home I discovered it blew out the transmission output shaft seal. Frustrating thing is I replaced it back in November, but it had gone hard as a rock and apparently contracted because it no longer fit snugly in the case. It looked worse than most 50 year old OEM seals.


I usually buy OEM parts except for seals and gaskets. I typically measure the seals and buy whatever's available online. I rarely notice a difference between OEM and generic. But lesson learned. I pulled all the seals from the motor again and ordered new OEM P/Ns from RevZilla.


I drained the remainder of the engine oil and it looked fine. No sparkles, no obvious heat/fraction damage on the cam. Pulled the clutch cover and inspected the oil screen and sump, same story. Thankfully I think I avoided a disaster

 

[stl360+450]

I'm glad your rear wheel didn't pass you when the oil started spewing out and that you were close enough to walk it home.

My 360G lost a key on the oil pump gear once and that put the bike out of operation immediately. I didn't know what happened other than bad noises, but the shortest path home went through a sizable city park on the walking path, so that's what I did.