I had an oil leak that left a fine mist on the RH side of the crankcase. I did the Verslagen head plug fix, and a new seal on the speedo cable, plus sealed the speedo fitting on the trans.  I took it for a 15 mile ride and there was more oil mist just below the cylinder.  This is really annoying after all the work I've done.  The side cover gasket is new and doesn't appear to be leaking.  Any suggestions?  I ran it for a while parked and couldn't see anything coming out.
BTW the 38-year-old head plug, while very loose, did not appear to have been leaking.

Oil leaks can be very difficult to locate - especially once your start riding at speed.

Several years ago I was getting oil up on the front right side of my fuel tank once in a while.  Sometimes I could ride all day and never have any oil - and sometimes I could go for a short ride and get the oil on the fuel tank.  After a long time searching, I discovered the O-ring on the speedometer drive tube was leaking - but it would only leak when I did a full throttle acceleration through several gears.  The wind while riding would somehow carry the oil forward and upward and blow it onto the front of the fuel tank!

More recently I spent a lot of time looking for an oil leak that would deposit a few tiny drops of oil onto the metal plate behind the starter.  It turned out it was an aftermarket head gasket that did not have the coating applied between the layers of the head gasket, and the oil was weeping out the front of the gasket - it was very difficult to spot on the shiny black head and cylinder.  A new head gasket solved the problem.

You need to clean the motor really well, then go for slow rides and look for the oil.....wind at speeds can blow the oil around and make you start looking in all the wrong places.  The nut at the front of the cylinder beneath the header is known to leak oil, the washers on right side cylinder studs can leak - and the right rear cylinder stud can also leak oil.  The center case can leak oil and drip off the left footpeg if the engine mounting bolt is loose.  Look at the O-ring on the engine oil fill plug - those can get old and leak.

Keep looking.

Darryl wrote on 07/23/26 at 14:01:47:


You might be onto something there.  The right side case has 3 locations that have the sealing washers.  These washers have a rubber inner ID that seals against oil leaks.

In the attached diagram - the bolts that have the number "7" have the sealing washers.

Yes, there is an O-ring on the clutch release shaft.

To replace it you have to remove the cotter pin and slide the shaft out....you will see the O-ring sitting in a groove machined into the shaft.