Vintage BMW Motorcycle Owners

While synchronizing the Dellorto’s I noticed a puddle of oil under the oil pan.

I thought it was the oil drain plug but it is dry.

After further investigation I found oil seeping from between the gear box and the engine.




What do you think, main seal, oil pump gasket? There is also a little oil coming from the pushrod seals too.

Gearbox needs to come off to diagnose?

Engine oil or transmission oil? Maybe it's the transmission input seal? Clearly the transmission has to come out to see where it's coming from.

How many miles on the bike?
If it is engine oil, (gear oil has a particular smell) and is not migrating back from the push rod seals, then it is most likely the rear main engine seal. 70K or so they can start to go.

So it is a big job, the transmission, clutch, and flywheel will have to be removed.

Note, it is imperative to block the crank at the front of the engine some way to prevent the crankshaft from being moved forward in the bearings. There is a shim in the back that can be dislodged if not done causing problems.

Also, you will need a special tool to properly seat the new seal properly.
The clutch reassembly will need a centering tool as well.

Check out Brook Reams or Boxer two Valve for possible videos on this. Good luck, St.

Thanks Kurt and Srankin for answering.

I watched the Boxer 2 Valve videos thanks and think are great.
Kurt, it is motor oil and I agree with you; transmission, clutch and flywheel need to come down.

The odometer was in pieces when I purchase the bike and has only 18k miles since restored. The motorcycle show many more miles. Over all the bike shows its age.



Since I purchase the R90S I have always wanted to repaint the bike.



There is funny story about the color, a former owner have it repaint to Daytona Orange but he was colorblind and received a Yellow Silver paint instead. He “noticed” or was told about the yellow until his son asked him about the odd color scheme.



I checked the VIN and it should be Silver Smoke.

What do you think, is this a good time to repaint the frame, fix some parts and repaint the body work? I need to remove the gearbox, swing arm, drive shaft….

And if so, would you paint it to match the VIN, back to Silver Smoke or Daytona Orange?

I like the color and would kept it
One and only and great story

Well for me, if the paint is decent and you don't mind the scheme, keep it as it is. IF you want it period correct for some reason then go with the silver smoke as original.

Looking at the pictures, it doesn't look like you need to paint the frame or am I just not seeing it?

I am probably the wrong person to ask about paint and stuff because I am picky but not too picky. I won't ever enter a bike in show so if the paint is not the exact shade or whatever, I don't care as long as it is not some weird color or color combination. Same goes for the frame, as long as it is not rusted or terribly scratched up, I will ride it.

So I guess I am saying fix what needs to be fixed, ride it and enjoy it first. Over the winter if you want a project and can afford it, maybe change the paint job. St.

Srankin, the paint photographs 60% better then reality but mechanically, other then the main seal leak, works perfectly.

Friends; are there a good restoration books for these 70's bikes, something equivalent to the Barrington?

I think it will be a good idea to read such literature before making a decision.

I found this post by #skychs there is a lot of information in here. Isn't it amazing how much information we have? Just a search away!

viewtopic.php?t=14846

LOL, as someone who grew up with shop manuals, I really appreciate some of the fellows who have taken the time to either take lots of pictures to show work or as in the case of Brook Reams and Boxer Two Valve, to make high quality videos.

Seems the newest versions of Clymer and hanses manuals are just about useless as they try to cover too many models of airheads in limited space. It makes it hard to follow when doing something for the first time. St.

I decided to refresh the R90S I will post as soon as I start, while I will post part numbers i decided to keep prices out or should I leave them together with the vendors?