1977 BMW R100RS Install Timing Chain, Crankshaft Sprocket & Bearing

I replaced the timing chain, crankshaft sprocket and nose bearing and the three oil seals in the timing chest cover. You can read about this work here:

The procedure for the 1977 R100RS is the same as the 1975 R75/6 as no major changes in these components was made. I link to the appropriate R75/6 procedures and show differences I found in the R100RS as appropriate.

I did this work in conjunction with replacing the major engine electrical componets. You can read about that work here.

Here are a few pictures and videos from the write-up.

Timing Chest Cover Exposed with Cover Puller on Crankshaft Nose
Timing Chest Cover Exposed with Cover Puller on Crankshaft Nose

Tachometer Drive Shaft Coming Loose
Tachometer Drive Shaft Coming Loose

Timing Chain After Using Bolt Cutter
Timing Chain After Using Bolt Cutter

Dial Indicator Mounted To Check Cam Nose Runout
Dial Indicator Mounted To Check Cam Nose Run Out

VIDEO: Checking Camshaft Nose Runout

Timing Marks When Sprockets Are One Tooth Out of Alignment
Timing Marks When Sprockets Are One Tooth Out of Alignment

Timing Chest Cover Installed
Timing Chest Cover Installed

8 thoughts on “1977 BMW R100RS Install Timing Chain, Crankshaft Sprocket & Bearing

  1. Hi

    I may have overlooked your procedure but I’ve looked several times for it..How does one replace the tacho drive seal?

    Regards

    Dave

      • Hi, I did see this section but you just casually mentioned that the bushing came out with the cable. Mine is solid having been in the cover for some 45 years. What would you suggest I do to remove the bushing?

        Dave

        • Hi Dave,

          If you mean the black plastic bush the cable ferrule sits inside of, yes it can be hard to get it out of the aluminum sleeve in the inner cover. This ought to help get it loose.
          1. Use some penetrating oil around the circumference and let it sit.
          2. Use your heat gun to warn the aluminum around the bush until the penetrating oil starts to smoke.
          3. Assuming the cable will slide back into the bush, insert it and then use it to wiggle the bush loose and out of the hole.

          If the cable slides out of the bush preventing your use of it to help pull the bush out, then I’d try this idea.
          1. Use a sheet metal screw and a drill. Drill a small hole into the side of the bushing through the cut-out in the aluminum sleeve the bush sits inside of.
          2. Thread the screw into the hole and tighten until the end of the screw just starts to penetrate the other side of the bushing.
          3. Grab the end of the screw with vice lock pliers. Try to rotate the bushing left and right to loosen it and then try to pull up on the screw to start getting it out of the hole.
          4. Once the bottom of the bush clears the cut-out, you can use a screw driver to pry it upward and I think that will get it to the point you can grab the top of the bush with the vice grips to twist and pull it out of the aluminum hole.

          I hope this helps.

          Best.
          Brook.

  2. Hi Brook,have been having interesting discussions on Facebook,concerning a R100S engine without a engine number stamped on it,the general agreement is that it was a replacement engine,which the dealer forgot to stamp,however the other thing was that a set of stamped numbers on the block(bottom right) as you stand in front of the bike,confirm that this is a replacement engine,i have these numbers on my engine,and i note they are present in your picture ,timing chest cover exposed…i am not convinced…there seems to be to many with these numbers,do you have any information or knowledge on this matter?.IAN.

    • Hi Ian,

      On my ’77 RS, the number “506420” is likely the casting number. So, all the blocks would have this same number until an internal change occurred that required a different block. That change may have happened when the oil cooler was introduced and if so, those blocks had a different casting number.

      Hope this helps.

      Best.
      Brook.

  3. This is what I thought, BMW Motterrad UK, did not know, they have given me the address of their classic department, so I have asked them the same question leading on to just how would you know if you had a replacement engine?, the guy on Facebook is about to sell his unnumbered engine on Ebay interesting, also plays hell with the mileage figures ,high mileage chassis low mileage engine . Many Thanks IAN.

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