Hi all:
Things progressing quite well. Inspected for safety yesterday, tag and insurance Monday on the road tues. Been quite an adventure so far.

Slight main seal leak, maybe 2 or 3 drops out the weep hole in a few days sittimg.. Bike has sat for a couple of years, would use heal this? If not would mobile one high mileage oil help, says it swells seals? Maybe it's not a big deal?

This winter going on to do clutch spline lube but was hoping just to shift trany back a little and use a brush.

Thoughts welcome.

I would take a couple days and pull the transmission.  Then you can do the splines, and replace the o-ring and rear seal.  It does't cost much to do,, mainly some time.  Then you will have the peace of mind for as long as you have the bike.

Ya, kinda thought a must do. However won't ride much this summer, maybe 1000 miles. Have to wait till snow flies.
Going to change the oil at 100 miles because it sat so long. Mobil one high mileage oil can't hurt or can it?

Does the residue smell like oil or sulfur? Transmission fluid can leak through that hole too.

To me, you're likely describing an output shaft o-ring leak. You'll only find out if riding more changes the picture if you ride more, you'll only prove Mobil's claims of seal repair if you use their oil product, testimonials aside. Modern oil is unlikely to hurt an engine. A main seal leak would be likely to output more oil through the weep hole, the engine would seem to be consuming oil at an increasing rate, and clutch slippage might become starkly apparent. 

My Brick had that o-ring start leaking—a few drops of oil on the shop floor, no pooling—and I kept riding it for ≈15,000 miles before the clutch's slipping at high passing speed on the Interstates compelled me to repair it so the miles-per-gallon numbers would improve.    During the leakage, the oil level in the sight glass didn't drop precipitously; I might have added half a quart in 5000 miles, and I did that only as a nod to responsible ownership. I replaced it, didn't touch the rear main seal and have been motoring happily since.

My point is, if the clutch isn't slipping significantly, if the garage floor or pavement beneath your parked Brick isn't becoming a reflecting pool, or if an oil slick isn't trailing your Brick imperiling tire traction for yourself and everybody behind you, enjoy as much riding while you can—the clock is ticking. Of course, this approach requires a certain level of throwing caution to the wind and perhaps replacing an oil soaked clutch disc when you replace the o-ring or whatever is ailing, but winter will come to the Northern climes soon enough to redirect attention back to so-called reality.

Nevertheless, to repair the leakage (regardless of its source), as Point-Seven-five indicated, the transmission will need to be removed so at that time, you can re-lube the transmission input shaft splines and clutch hub appropriately when you're finishing the job.

The way I look at it though, peace of mind—like courage—seems to be a condition independent of external circumstance; both happen because we will them to happen; admittedly though, having oil remaining where it belongs is desirable from mechanical and conservation standpoints.

It could be either the main seal leaking or the clutch nut O-ring. It's usually the latter in my experience.

Using HM oil may or may not work to fix your leak.

If you replace the clutch nut O-ring then use a 19x4 FKM/VITON O-ring. They are better and longer lasting than normal O-rings.

When my RT started the tell tale sign I decided to keep riding it as I was a little over 60,000 miles. I knew at that stage it would be clutch as well just by being sensible. I got to 78,000 miles before doing the job and the first time the clutch clipped was riding the bike onto the lift.

I really got the last out of the clutch too, there was nothing left on the friction plate so I was happy. 

My thought now is if the seal leaks dont panic, ride it until the clutch gives out.

As a farmer I have got along okay with - if it ain't broke don't fix it.
Glad to have a generic version of the o ring, anything to stay out of the motorad clutches!

Bricklayer wrote:In regards to the: 19x4 FKM/VITON O-ring Researching this I came across different "hardness" ratings, colors, and application uses. Anyone have any specifics on what one would look for in obtaining this. TIA.

I believe the 2.45USD OEM part is rated HE/BNTH. 

Well put about 300km on the bike with "blue devil" rear main liquid sealer in fresh oil. After each ride I put waxpaper under the bike drop slowed and now gone! Could have just needed riding or the devil worked will Never know. It was worth a shot.

Sounds like you are getting into nice shape.