I put together a series of pages about BMW airhead motorcycle electrical systems. It strikes me that electricity in general, and motorcycle electrics in particular, are dark mysteries to many, so I thought I’d shine some light [puns intended 🙂 ].
Lack of understanding hinders confidence when diagnosing and working on electrical projects. As these bikes age, the electrical system is prone to problems as corrosion and neglect makes them behave badly. More owners are having more electrical problems but seem less able to get to the root cause of the problem.
I think one tool that many avoid using is the wiring diagram. The spaghetti of lines, symbols and notations makes the eyes glaze over. “Oh goodness, where do I start?” is the common response to the advice, “Look at the wiring diagram.”
5 Series Wiring Diagram (1970-1973) (Source: Haynes Manual) –> CLICK TO ENLARGE
I’m not an electrical engineer, but I have taken time to learn the basics, have collected comments and input from well respected airhead mechanics and dug into how BMW applied electrical theory when they designed the /5 electrical system. I’ve learned a lot from various reference sources that are scattered about the internet, so my articles include a bibliography of various useful resources. That way both you and I have a nice set of reference materials to consult when problems come up.
I have published three articles (so far), Basics and two about the /5 series: 5 Series Electrical Circuits and, 5 Series Electrical Components. I chose the /5 series to start with because I believe it’s the most popular airhead series for restoration.
I hope to write an Electrical Circuits and Electrical Components document for the /6 and /7 series up to 1984.
Here is the table of contents from the first three documents.
This is the most critical, precise piece of work I’ve taken on. Before doing this project, I did a lot of research. I had access to special tools, a shop press and advice from two local airhead mechanics. Without those resources, and spending a couple months trying to learn what I needed to know about this work, I wouldn’t have attempted to do it.
Despite all that, I managed to overlook a new, but wrong size, $2.95 circlip that holds the cam roller on it’s pin. It separated company from the pin about 2000 miles after I finished rebuilding the bike. I was in Indiana at the time on my way to the 40th RS rally in Pennsylvania. Mr. Cutter, who was attending the rally, stepped in and devoted a Sunday to save my bacon. Watching him do the work in a day I had labored over for weeks reinforced the value you get from someone who has spent 45 years making mistakes and learning from them so you don’t have to 🙂
So, in retrospect, I should say I relied on three airhead mechanics to do this work 😉
In two months since I completed the build, I’ve ridden the bike 4,400 miles. I named it “Gonzo” as I like to name my bikes after Muppet characters :-).
Gonzo Starting Mileage On Departure for Pennsylvania
I rode it to the 40th R100RS anniversary rally in Pennsylvania and back and had a problem with the transmission about 350 miles from the rally that required me to stop riding until it was fixed. That work was done by Tom Cutter of Rubber Chicken Racing Garage and I completed the ride home only one day late.
I documented the issues, corrections and updates I made from the first engine start through the end of my ride back from Pennsylvania here.
Here are links to two set’s of pictures, the first are the ones I took on the trip and at the rally, and the second are by, Andy Muller, a photographer, who is the proud owner of the 40th RS sold in the US so of course he brought it to the 40th RS anniversary rally. What a nice bit of serendipity.
My route to the rally follows US 36 which passes through Hannibal, MO.
On the Way to the Rally
Mississippi River, Hannibal MO
Mark Twain Statue at Hannibal Waterfront
I planned a shorter ride the day I arrived in Hannibal so I could spend some time visiting the Mark Twain museum. I stayed at a B&B in a 19th century home, the Dubach Inn. My suite was on the second floor with it’s own staircase and balcony where I enjoyed a Gin and Tonic at the end of the day.
Dubach Inn, Hannibal MO
The city turned the block where Twain grew up into a museum that includes his home, his father’s justice of the peace office, Becky Thacher’s house, and the home that was occasionally used by the street urchin he crafted Huckleberry Finn from. I really enjoyed the exhibits and learned a lot more about Twain’s life and the impact of it on his personality and ultimately how it became the source for many of the books that made him famous.
Reconstruction of Huck Finn House at Mark Twain Museum
Mark Twain Museum
Mark Twain Museum
Mark Twain Museum
Mark Twain Museum
Along US 36 I saw a number of signs about the pony express and the stops and routes they used. A rider would take the mail and ride a set distance each day and then hand the mail pouch to another rider who continued with the mail. The first rider then took mail from a rider coming the other direction and returned with it to where he started. This shuttling operation moved the mail from St Louis to California. Little did I know at the time that the Airhead Pony Express would be enlisted to deliver Gonzo and I on the last leg of the trip to the rally.
The next day I stop at a hotel in a suburb of Indianapolis, IN. At the start of the day I enjoyed riding on two lane roads although I was riding in a light rain and some fog for awhile. I took some state and county roads to avoid the heavy traffic I recall from a previous ride to the east coast on I-70 through Indianapolis. Alas, I poked along through Indianapolis suburban sprawl, construction zones for the last hour. It was a long day.
On the Way to the Rally
On the Way to the Rally
After I got to the hotel, I thought I heard noise from the transmission. I had replaced the bearings and seals, my first time doing this work, so I was worried I had failed to do the work correctly. But when I got up the next morning under a dull gray sky with light rain and drizzle and started the bike the transmission seemed to be quiet. I chalked up the noise I thought I heard to my paranoia and being hyper-sensitive to the new sounds from an unfamiliar bike and transmission.
I headed out in the drizzle and mist on my way to West Virginia near the Pennsylvania boarder to my next hotel. At my first gas stop late in the morning, I could hear the transmission noise again. It was louder and clearly something was not right. I still had another 200 miles to my hotel and no hope of finding any airhead transmission experts in this part of the country. At the end of the day I would still be about 350 miles from the rally location in Pennsylvania.
On the Way to the Rally
40th R100RS Anniversary Rally
Diagnosing the Problem
Tom Cutter, one of the best airhead mechanics and an expert transmission builder, was coming to the rally and he lives pretty close by. When I got to my hotel in Triadelphia WV I called him and described what I was hearing. I told him I planned to bring the bike to him and leave it and I would figure out how to get back home. He told me not to worry. He would start work on the bike on Sunday right after the rally and would get me back on the road as soon as possible. The huge weight of worry and dread that had been weighing on me all day suddenly vanished.
He had me do a number of tests including draining the transmission at an auto parts store to see what came out. When I got there and bought some gear lube and a drain pain, it was raining lightly and the light was fading as I started to drain the gear box in the parking lot.
Draining Transmission Oil at an Auto Zone in Triadelphia West Virginia
When I removed the drain plug, I found a circlip stuck to it. It secures the plastic roller that rides on the shift cam to a pin on the shifter arm. That can’t be good. I used my cell phone to send a picture to Tom. His advice was to not ride the bike any more if at all possible. I was tired, a bit wet and dejected as I rode Gonzo five miles back to the hotel in the dark to get something to eat.
Circlip from Shift Quadrant Roller – Shouldn’t Be In The Transmission 🙁
The Airhead Pony Express
After dinner I decided to post a note to the newsgroup used by rally members for communication to see if anyone might be in the area with a trailer that could take Gonzo and I to the rally hotel in Pennsylvania and then went to bed for a night of fitful sleep as I reviewed scenarios of how to get to the rally and all the changes I had to make to my return hotel reservations since I was going to be delayed. On top of that, my credit card had been fraudulently used on the internet and the card company had cancelled it. Ah, it never rains but it pours 🙂
The next morning, I saw a note from Duane Wilding who lives near Annapolis, MD. He offered to load his bike on his trailer instead of riding to the rally and it had room for mine. The detour would double the time for him to get to to rally changing a 5 hour day of riding to more like 10 or 11 hours of towing. I didn’t see any other offers so I called him and asked him to come pick me up. It would take him an hour and a half to get the trailer hooked up and and I agreed to call him if in the mean time I heard from someone closer who was able to help.
I started to call my hotels to put my rooms on hold, called my wife to let her know what was happening and as I scrolled through other email, I suddenly saw a reply posted by Scott Mercer right after I sent my note. I had missed it when I first looked at my Email. His note said he was an hour and a half away and had a truck with his bike in it and there was room to add mine. I connected with him, confirmed he was still able to come by and pick up Gonzo and told him I’d call him back as I had to cancel my ride from Duane who was going well out of his way to help.
When I called Duane back and told him to stand down, I reached him just before he was about to start driving my way. And then I got two more calls, one from Scott’s friend, Tom Gaiser, who was bringing his R90S in his pick up truck and said he would come by in case we needed help getting Gonzo in Scott’s truck. When I hung up I got a call from Keven O’Neil who was bringing his bike on a trailer following my route from Indianapolis. He too said he would stop to help and in case my bike didn’t fit in Scott’s truck, there was room on his trailer. I had gone from famine to feast. I was overwhelmed by the generosity and support from these Airheads. What a great bunch they are.
Airhead Pony Express Arrives
Mike Mercer’s Trailer with Tom Gaiser Supervising
Gonzo in Mike Mercer’s Trailer Next to His Mint 1978 Motosport
Five hours later we turned off the Pennsylvania Turnpike and stopped next to an appliance that was as ubiquitous as cell phones are today when the RS was brand new. I couldn’t resist; I went over, picked up the handset and it had a dial tone. That pay phone still works for it’s intended purpose, just as my 1977 RS does. How unexpected, and fitting to find this relic on my journey to a 40th R100RS anniversary rally.
Working Pay Phone at Our Exit on Pennsylvania Turnpike
We pulled into the Holiday Inn parking lot, unloaded Gonzo and parked him in the growing group of RS bikes in the parking lot. Then Scott and Tom drove to their hotel 20 minutes away.
The Rally at Todd Trumbore’s Home
The next morning, Friday, I got a ride to the rally at Todd Trumbore’s home where the rally was held from Mike Cecchini who brought his bike on a trailer.
Todd Trumbore Host for 40th R100RS Anniversary Rally
I spent the day in awe of the variety of bikes parked outside Todd’s “Bavarian Bike Barn” including a Munch Mammoth, an ISDT race bik, a replica of the Udo Gietl prepared R90S that won Daytona in 1976 and the first AMA Super Bike championship, A Mondial and of course, multiple examples of well cared for RS bikes and more first year bikes than I’ve ever seen in one place a one time.
Here is a short video of starting the Mammoth and the sound it makes.
Some of the 40th RS Anniversary Rally Attendees and Their Bikes
There were talks by Hans Muth, Udo Gietl, and Tom Cutter, and numerous conversations with fellow airhead RS owners about their bikes. Hans graciously designed the logo on the far right and Todd did the other two. I have all three stickers from the rally and will find a suitable place of honor for them in my work shop.
40th RS Anniversary Rally Logo’s Designed by Hans Muth
On Saturday, Mike put Gonzo in his trailer and as the next airhead pony express rider, faithfully delivered us to Todd Trumbore’s. We unloaded Gonzo and I rode him up Todd’s driveway so I could say with a straight face that I rode him to the rally. 🙂
Gonzo Getting Tied Down in Mike Cecchini’s Trailer
My 1977 RS – “Gonzo” – Parked Among His Fellow 1977 R100RS Bikes
Mike Cecchini’s R90S Fitted in RS Body Work – Beautiful !!!
Meeting Hans Muth and Getting Gonzo an Autograph
It took a year of work rebuilding the bike and several adventures along the way while riding him to Pennsylvania, but I met Hans Muth, shook his hand and got his autograph on Gonzo’s factory inspection sticker. An amazing end to a year of work and adventure riding to the rally.
Shaking Hands with Hans Muth Next To My 1977 R100RS
Hans A. Muth Signature on My 1977 R100RS Factory Inspection Sticker
Fixing Gonzo’s Transmission
Saturday evening, Tom Cutter and I loaded Gonzo on his trailer and I rode Tom’s “Fake S” R100/7 to his house that is about an hour away. What a treat, to say the least. 🙂
Gonzo Loaded in Tom Cutter’s Trailer Next to His R Nine T
Tom Cutter’s “Fake S” That He Let Me Ride – What a Hoot and Very Kind of Him
On Sunday, he pulled the transmission out, disassembled it, cleaned and inspected it, replace the circlip and roller, and reassembled it. He found no other damage to the transmission. After careful measurement of my circlip and a new one, it seems the new one I installed is not the correct size. I failed to catch that when I installed it since this was the first time I had opened a transmission so I had no experience with the parts. That said, in the future, I can compare the new parts to the old to reduce this kind of mistake in the future.
My Circlip (Left), Correct New One (Right)
the circlip was a bit too large compared to the new one he installed. Either it was a defective part, or I damaged it when I installed it. On Monday morning, we installed Gonzo’s transmission and Tom took care of a couple other assembly mistakes I made. By 2:00 pm Monday, I was back on the road heading home.
Going Back Home
I rode on US 50 most of the way until Topeka Kansas where I got on I-70. I went through Athens, Ohio on Tuesday and stopped to meet Kent Holt of Holt BMW who provided the paint and a great deal of advice when I tried my hand at painting. He took me on a tour of his facility and he spent almost two hours talking with me. What a treat/.
Marvin Greeted Me at Holt BMW with Coffee 🙂
Kent Holt in his Work Shop
Kent Holt’s Ride with Custom Paint Work
I stopped in Jefferson City, MO to stay at a B&B housed in a civil war ear home built on a high bluff over looking the Missouri River and had dinner at an Irish pub around that corner, Paddy Malone’s, that is one of the oldest continuously operating pubs in the mid-west. There is a flag from every county in Ireland on the ceilings and walls. A great place to relax.
Cliff Manor B&B Jefferson City MO
Gonzo Resting at the Cliff Manor B&B Jefferson City MO
Missouri River From Patio of Cliff Manor B&B Jefferson City MO
Beer Board at Paddy Malone’s Pub in Jefferson City MO
Jefferson City MO Irish Pub with County Flags
The next day I rode to Hays, Kansas. In the afternoon, I had 30 MPH cross winds for several hours and at one point, the bike thermometer showed 102 F. The air conditioned lobby of the hotel was very refreshing 🙂
I arrived home on Friday about noon after riding over 3,300 miles in the past 11 days, meeting great people who love BMW bikes and especially the RS and attending a fabulous rally celebrating the 40th anniversary of the introduction of the R100RS.
Ending Mileage – Over 3,300 Miles
To all the airheads at the rally who directly helped me get there or took a moment to talk with me and provide words of encouragement that lifted my spirits, thank you from the bottom of my heart. RS riders in particular, and Airheads in general, are some of the nicest folks you could ever want to spend a weekend with.
After finishing the rebuild of this bike on July 21, I prepared it to ride out to the 40th RS anniversary rally in Harleysville, PA (yes, “Harleys” ville). I put almost 1,000 miles on the bike prior to heading to the rally and corrected a number of problems. I also set it up for touring by adding my old Garmin 2610 GPS, a set of Hepco-Becker panniers I had on the R75/6, my Wolfman tank bag, and a pair of Kathy’s Journey fairing bags.
Wolfman Tank Bag with Kathy’s Journey’s Fairing Bag
Ready for Touring
I decided to name this 1977 R100RS, Gonzo. My wife and I have a habit of naming our motorcycles for Muppet characters, and after some thought, Gonzo seemed to fit this one.
I plan to ride on US highways on my way to and from Pennsylvania avoiding the “super slab” as much as possible. Unlike my Iron Butt rides, this ride will be leisurely with time to smell the flowers allowing five days to ride out and five to ride back.
I packed a maintenance kit with extra tools along with clothing and other essentials for a trip.
Tools and Spares List
On Sunday I took a picture of the starting mileage and right at 8:30 am I got on US 36 no far from my home planning to stop about halfway across Kansas.
Starting Mileage with Gonzo Ready To Roll
US 36 shares I-70 for the first 30 miles with the usual hurrying and scurrying traffic even early on a Sunday morning. When I turned onto two lane US 36 at Byers, CO I enjoyed the relaxed pace with no traffic on a beautiful sunny morning.
US 36 in Eastern Colorado
Traffic Conditions on US 36 in Eastern Colorado
There is race track on US 36 and I stopped to take a picture of the cars coming down a hill. I pulled over on the shoulder, put Gonzo on the side stand and got off to get a picture of it in the foreground with some race cars going by in the background.
Race Cars on the High Plains Race Track Along US 36
I sensed something wasn’t right and as I moved my eye from the view finder, I could see Gonzo was rolling forward and starting to fall over on the left side. I dropped the camera and grabbed him from the right side, but he was tipped too far over on the left and I could couldn’t pull him upright. The best I could do was slow the fall. A slow motion CARUMMPPP followed as he went down on the edge of the top fairing panel and then lay on the side of the road leaking gas onto the shoulder. In my hurry to get the picture, I didn’t put the bike in first gear before putting it on the side stand. There was a very slight down hill grade and of course, it crept forward as I was framing the picture until the side stand folded up.
I quickly went over to the left side and pushed him back up on his feet (it’s good to know I still have the strength to pick up an RS with loaded panniers) and then put him on the center stand. The top left faring panel is scraped on the edge and has a crack and another hairline one above the turn signal. Those are exactly the places I repaired when I stripped all the body work off, so a previous owner had the side stand fold up too. There is the also the usual scrape on the lower edge of the valve cover. Gonzo is “broken” in at last 🙂 Yes, that’s a smile, not a frown.
Result of a Tip Over – Oooppps
When I finish a rebuild, I’m always nervous about getting dings or scratches on the finished bike. But, eventually, these show up. So I have come to appreciate the arrival of the first ding, scratch or dent because I don’t have to worry any more about trying to keep the bike pristine.
I built Gonzo to be a rider, not a hider. Although I would have preferred my stupidity didn’t result in damage to the fairing, I can’t let that interfere with the enjoyment of riding him nearly 4,000 miles over the next week and half. “Endeavor to Persevere”, as my Email tag line goes. So I motor off heading to Kansas.