I am going to replace the timing chain, crankshaft sprocket, crankshaft nose bearing, and the front main seal. I’m also going to pull the crankshaft to inspect the main bearings.
But first, I have to remove the electrical components and wiring inside the front engine cover that includes the diode board, alternator and ignition sensor, aka, the “bean can”, aka, the “electronic points”. I plan to upgrade the alternator and diode board to a 400 watt system. I also plan on opening the bean can to lube the advance mechanism and replace the Hall effect sensors.
Here is the before and after pictures.
Diode Board, Alternator, Ignition Sensor Are Inside Front Engine Cover
And, I shot a video of this work which is a bit long at 20 mins.
VIDEO: 1983 BMW R100RS Remove Diode Board, Alternator and Ignition Sensor
My goal in the video is to explain more about what the wiring under the front engine cover does and how it’s routed, as well as show how to remove all the components, so that added to the length. I’ll try to keep future videos shorter.
The inside of the bell housing as well as the shelf under the transmission showed oil leaks, so one, or all, of these are the likely culprits.
Grunge Inside the Bell Housing Suggests O-rings and/or Rear Main Seal Leaks
Oil & Grudge On The Shelf Under The Transmission
When I opened up the oil pump to take measurements and do a visual inspection, I decided that I had to replace the oil pump due to a lot of wear and tear to the rotors inside the pump. You can see how I removed and measured the oil pump here:
When I first got the bike, in debugging a low oil pressure light that came on, I discovered that the oil filter high pressure bypass valve was hanging by a thread. So, unfiltered oil was circulating, but I didn’t know for how long. Based on the condition of the oil pump and the scores I found in the rod bearings, I think unfiltered oil circulated for while. Not what I wanted, but I’m glad I took a look at the pump.
And, you can see a short video that summarizes the work here:
Due to what I found with the oil pump, I’m making a detour on the project. I’m going to pull the crankshaft to inspect the main bearings. I suspect I won’t like what I find there either, but it makes sense to take a look.
Gonzo (my 1977 R100RS) and I are going to be on the road again on our way to Todd Trumbore’s home where he is hosting his third airhead 40th anniversary celebration of bikes designed by the legendary Hans Muth, on September 19-22, in Harleysville, PA. (Yes, an ironic location for a BMW airhead rally 🙂 ) This time Todd is celebrating 40 years since the introduction of the iconic R80 G/S and the R65LS models in 1979. Once again, Hans will be in attendance along with a notable list of other airhead and motorcycle legends who will be speaking. You can see the details here:
The first rally Todd hosted was in 2014 for the R90S and the second was in 2017 for the R100RS, which is the rally Gonzo and I first attended. Even though my garage does not yet include an R80 G/S or R65LS, Todd was happy to let me attend the festivities despite riding “only” an RS.
The R80 G/S and R65LS are the last two designs Hans developed for BMW before starting a design studio, Target Design, with some friends, Jan Fellstrom and Hans-Georg Kasten. One notable design from the Target Design studio was the Suzuki Katana in 1980. I find the lines of the R65LS and Katana are similar, as if Hans extended the design vocabulary the BMW R65LS and to the design commissioned by Suzuki for the Katana.
Suzuki Katana-To Me, It Echos The Design Vocabulary of the R65LS
When Gonzo and I went out in 2017, we had an adventure when the shift cam retaining circlip in Gonzo’s transmission came off the shaft. The BMW dealer I ordered it from supplied the wrong size circlip and I was not attentive enough to notice. Gonzo and I ended up being transported to the rally hotel by Scott Mercer with assistance from Tom Gaiser, and Keven O’Neil. Tom Cutter, at Rubber Chicken Racing Garage, one of the best airhead transmission re-builders, was a speaker at the rally and put Gonzo on his trailer while I followed him to his shop riding his “most excellent” R100 “Fake S” bike. He took apart the transmission on the Sunday after the 2017 rally while I watched and assisted with cleaning parts, and I was back on the road that Monday. Here is the story of my adventures going to the 40th anniversary of the RS rally in September 2017.
Although Gonzo and I are very appreciative of Tom’s generous assistance. we plan to avoid imposing on him again on this trip. 🙂
Since I \didn’t complete the entire trip last time in 2017, I am going to take the same route out and back this time. Somehow that seems appropriate.
Gonzo now has “matte” clear coat, which is correct for the 1977 RS bikes, but due to my failure to communicate with my painter, he was repainted with gloss clear coat back in 2017 when I did the restoration. He is also sporting the commemorative badge Todd provided to the participants of the 2017 R100RS rally. I think it’s a very nice touch and a lot classier than the cheap decal BMW originally used on the cowling in 1977.
This bike has a front master cylinder that is integrated into the Magura throttle assembly and a rear Brembo master cylinder. All three calipers are Brembo F-08 series with dual 38 mm pistons. I disassembled both master cylinders and inspected them. I repainted and rebuilt the rear master cylinder using a Brembo rebuild kit. Unfortunately, I found the front Magura master cylinder bore and internals were badly rusted and pitted, so I had to replace the front master cylinder rather than rebuild it. Even though I didn’t have to rebuild the front master cylinder, I show how you rebuild it and the rear master cylinder in this document.
I disassembled all three calipers, inspected them and found they were not corroded or pitted so I repainted and rebuilt them using a Brembo caliper rebuild kit. The same kit is used on all three calipers. You can see how I did that work here: