I’ve collected information that should help someone who is interested in doing rebuilds on older BMW motorcycles. The material is organized by each particular project.
Links to write-ups about the work I’ve done on all these bikes should be visible on the left side of any write-up page in the navigation bar, as is the case with this page. And, toward the end of each of the rebuild summary pages below is a list of write-up pages organized by parts fiche major heading–for example “11” is engine, “13” is fuel preparation, etc. There is also a link to a rebuild resource list to help you locate parts and advice and services, and a link to documentation about the airhead electrical system that is a work in progress. Happy rebuilding.
My first project was my original owner, 1975 R75/6 with 103,000 miles that I built into a R75/S replica of the famous R90/R100 S models. The next one was a two-owner, 1973 BMW R75/5 with 97,500 miles. I always wanted an R100RS and found a 1983 bike with 83,000 miles that needed a lot of TLC. I got it running reliably and then I got side tracked. I found a first year 1977 R100RS with less than 35,000 miles. So I switched my attention to the 1977 R100RS in hope of completing the rebuild/restore in time to attend a 40th anniversary celebration of the release of this historic motorcycle in September 2017. I did complete that rebuild in time to ride to the celebration in Pennsylvania and back, and then completed the 1983 R100RS build converting it into an RT model.
My current project is a charity rebuild of a 1983 R80ST. I will auction this bike and donate all the proceeds to the Motorcycle Relief Project, which sponsors motorcycle rides with therapy for military and first responders suffering from PTSD.
BMWMOA Magazine 1977 R100RS Rebuild Articles
At the invitation of the BMW Motorcycle Owners Association (MOA) magazine, I wrote about the 1977 R100RS rebuild project and the ride to the 40th anniversary of BMW’s release of the RS model where I met the designer, Hans Muth. Here are links to the three articles I wrote.
- November 2017, pg 62: Part 1-Rebuilding a First Year R100RS
- December 2017, pg 42: Part 2-Rebuilding a First Year R100RS
- January 2018, pg 63: Part 3-Rebuilding a First Year R100RS
Please be advised that there is no representation of the accuracy of any of the information presented on these web pages relative to BMW motorcycle maintenance or modification and that the material is presented for information purposes only. In no case will I be held liable for injury or damage (consequential or otherwise) resulting from or arising out of alterations you make to your motorcycle. The reader should recognize that motorcycling is a dangerous activity that can result in injury or death, and that the alterations portrayed on these web pages can and will change the behavior and performance of your motorcycle, possibly with fatal results. You are encouraged to seek qualified assistance before undertaking any of the procedures outlined here, and are here by notified that, should you decide to proceed, you do so at your own risk.
2021-02-26 Fixed broken links to BMW MOA magazine articles on 1977 RS rebuild
I hope you don’t mind me writing, I have an electrical issue I cannot fathom out.
Having rebuilt my BMW R75/5 and installed all new electrics I have an issue with my indicators not working. Everything else is OK so far but not started the engine yet.
Indicators do not flash. Indicator relay (new) clicks when 12.6 volts are passed. I have 12.6 volts at the relay mount and all the wiring to the new switch is good. If I bridge the connections on the relay mount and switch on indicators, left and right work constant, as does the indicator lamp. My only guess is the relay is bad?
Any advice would be appreciated.
Great Work by the way.
The pictures of your resto-mod are gorgeous !!! What a nice piece of work you have done.
So, /5 and turn signals won’t signal.
1. Can you hear the flasher relay “clicking”?
– Relay is closing inside, so likely ok.
2. There is no ground wire to the bulbs on the /5 which causes problems with the lights working.
– Take a piece of wire and ground it to the frame. Touch the other end to the base of the bulb. If the bulb flashes, the ground path is dodgy.
– The ground path for the front turn signals goes through the turn signal housing, the turn signal stalk, the fork tube, the steering head bearings, the steering stem to the frame. Obviously this is a “tortured” path which is why the /6 series includes a ground wire to the the turn signals.
– If your temporary ground wire makes the bulbs flash, create a permanent ground wire.
3. The flasher requires a filament bulb of the correct resistance or the flasher circuit will not work correctly.
– LED bulbs can cause this problem.
4. Is there a break in any of the turn signal wires, front or rear?
– This will reduce the resistance of the flasher circuit and cause this problem
5. Is any bulb filament burned out?
– This will reduce the resistance of the flasher circuit and cause this problem.
I hope this helps.
Hi Brook, what do you think a fair retail value of a completed restored R75/5 just like yours?
Just an estimate for reference
The value of that specific bike is “priceless”, as it was my wedding present to my wife back in 1978. 🙂
For generic R75/5 bikes, I have no clue what the market thinks these are worth today. As in all “classic” motorcycle sales, it has a lot to do with the fickle nature of what’s in vogue and what’s not. And any sale depends on how much the seller wants and how much the buyer is “Jonesing” for the bike.
To get some idea of what a bike is worth I usually start with the Kelley Blue Book for motorcycles Then I look at past sales online at Craig’s list, Cycle Trader’s and Bring A Trailer, for example, making adjustments for the condition, mileage and location.
To be clear, on all my restore/rebuild projects I’ve invested more in parts and tools than any of the bikes are worth according to KBB. But these projects are my form of therapy, so if I include the hours I’ve spent working on them and convert that to psychiatrist fees, I save enough on each bike to afford two or three more projects, so I’M WAAYYYYY AHEAD of the game. 🙂
I hope that helps.
R80/7 rear main seal
Indeed, there is one.