Aloha,
after riding hard my 1995 Sporty with 1200 conversion I found today an big oil spot under the bike.
It came from the gearbox vent under the seat.
After checking the primary I figured out there was 500ml (1/2 quart) engine oil over the limit.
I normally use the Rev Tech 20W50 engine oil and the Rev Tech Sportster Trans fluid in the primary/transmission.
I know the difference betwean the taste of engine an transmission oil.
It's definitely engine oil in the transmission.
While I'm the only mechanic since the last 29 years I know there is no bad filling.





So my suggestion is a bad sprocket seal.
Am I right with my guess?
Anybody had the same topic in the past?

 

On my '99 RK I had a mysterious leak, the short of it was the primary shaft seal was leaking. Transmission was leaking oil where the shaft went into the primary. Not familiar with your system, just sharing my experience.

 

How about cleaning everything up, and then keep an eye on where it first appears? Can't imagine how engine oil is getting in the primary: it is a dry sump

 

I found my leak using a dye kit off Amazon. No dye leaked from the primary, nor engine, finally traced the leak to behind the primary using the dye and UV flashlight.

 

It's very possible the crankshaft seal is leaking, that's the only place engine oil can enter the transmission. Hopefully, it's not too bad of a repair. I think someone recently posted about a similar issue.

John

 

Interesting that there’s oil on the side of the seat.

 

Same thing I was going to say, Oil had to come from somewhere, Either to much, or entered from another area,

What about the engine/trans, is it half quart low?

 

Aloha,
the oil comes from the gear box breather tube under the seat.
Probably from to much oil in combination with preasure from the crank case.

 

clean it up run it check with a black light

 

Check the oil in the engine