Restoring a 1973 BMW R75/5 Motorcycle

January 17, 2009

Schneider is no longer doing business

Filed under: R75/5 — Penforhire @ 6:51 am

I just discovered that Bill Schneider, the owner of Schneider’s Inc, was successfully sued over his “Sidestand Fixer” and driven out of the business he ran since the 70’s. That is why you will not find Flip-a-Lever’s for sale any more. I hear he has an inventory but I have no idea how you’d get one. Hopefully he’ll sell to someone else who will distribute.

The Sidestand Fixer was a conversion to stop the auto-retracting sidestand on later BMW models. My /5 does not auto-retract. I imagine someone installed it, forgot to kick up the stand, and crashed in a left hand turn. I am outraged that he could sue because the function and risks are obvious! Yes, this device bypasses a manufacturer safety feature. Buyer beware. Grrrr…


October 11, 2008

The journey is everything

Filed under: R75/5 — Penforhire @ 3:50 pm

The journey of resurrecting this rust-bucket R75/5 was well worth it. I do not regret a single moment or expense. Without getting too “Zen and the Art of Motorcycle Maintenance” on you, I was able to commune with my late father in ways I was unable to while he lived. I greatly expanded my mechanical boundaries and what I think is possible. I am pleased I could inspire some of you to fight entropy on your own project bikes and that I could even give some technical guidance (who’d have thought it?!).

The change to Mikuni carbs made this bike reliable enough for me not to fear long distance travel on it. Idle still varies cold-to-hot but I think that’s the nature of simple carbs. It has NEVER failed to start since the change, though I did pull the plugs to clean and gap them once (color was a nice tan, no soot) and I’m probably due to check valve clearances again.

I changed ALL the fluids again at least once. Great for my paranoia but nothing seemed strange in fluid colors or textures.

I added a small handlebar mount windshield, careful on size because these are known to cause instability! Highway windblast rises quickly to annoy and tire me at 65+ MPH, not to mention when trying to hang with the big dogs at higher speeds. Under, um, “controlled test conditions” I found the bike is capable of about 100 MPH flat out, with bags, for quite a distance and nothing odd happened in terms of handling. My arms might be longer from hanging onto the bars but it otherwise rides fine at the ton. I added that windscreen to remove some pressure. I think it works for that but does nothing to help with turbulence or noise.

I changed the mirror stalks for CRG’s “Hindsight LS” mirrors with their internal end-adapters in my bar. The OEM mirrors did not provide a good view behind my wide shoulders. CRG’s bar end mirrors give me a better view and really look good, in a cafe racer way. Icing on the cake is how they are designed to fold to ease lane splitting. My opinion is two thumbs up, in spite of their high price.

I had a little trouble with the EnDuralast charging rotor. It got loose, detailed in my XKE blog, but I think I have it licked after using lapping compound to mate it to the crank end. I can tell it works because my Battery Tender never has to charge the battery after a ride. It goes immediately to float charging (solid green light).

Let’s see, I also had to re-glue one of the tank panels. Gorilla snot was not quite enough!

I sold my FJR1300 a while back so I could focus exclusively on riding the /5. The magic carpet ride was too tempting on a day-to-day basis and I was worried I wouldn’t exercise the /5 enough. So now I feel like I’m at the end of the journey. And to be honest, the journey was far more rewarding than the destination.

The /5 is the king of cool. It isn’t the oldest bike to show up at BMW gatherings but it is among them. I think it might be the oldest ride I see in the SC-MA runs. I’m surprised by how few /5’s I see on the road. You know how you’re sensitized to seeing whatever you ride? Well there just aren’t as many /5’s on the road as I expected. People eyeball it wherever I go but there must be something intimidating about the marque because not many people ask me about it, but everyone looks.

After dedicating myself to this machine, both in commuting and 300+ mile sport-touring days, I feel I’ve given enough time and consideration to decide that riding it is not my cup of tea. I have a need for the responsiveness and one-with-machine feeling I get from more modern rides, plus ABS because I’m willing to admit I’m just not THAT good a rider when it is wet, dark, and I’m tired at the end of a long day’s ride. I may go to something more naked than my FJR, like the R1200R, but I haven’t decded yet.

When I started this project I never thought I’d say this — do you know anyone looking for a restored and upgraded /5 ? I know most of you will think I’m nuts. That’s nothing new. As I get older I gain apprciation for Clint Eastwood’s line from Magnum Force, “a man’s got to know his limitations.” I can’t see myself continuing to use this as my sole ride nor properly maintaining this machine if it is not. It will crush me more to see this machine go to seed than to not possess it. I could mothball it properly but that’s not a good answer. This bird should fly.

So I’m asking $6,500 for it and a promise whoever buys it will ride it, as I will until it sells. Maybe I won’t be too upset if it doesn’t sell but it feels like the right thing to do. I’ll post a for-sale eventually on the Airheads site and elsewhere but I figure I’d offer it here first, among those who took the journey with me. And if someone asks what work was done you can just point them to this blog!

Remember, the journey is everything!

November 2, 2007

B’bye Bing!

Filed under: /5, 1973, airhead, BMW, BMW motorcycle, motorcycle restoration, R75, R75/5 — Penforhire @ 3:31 pm

Yes, beaten into submission by my carbs. If you don’t already know, my new insane vehicular project can be found at and that is one reason I haven’t been “here.”

You probably thought that over the weeks since my last post I’ve been sailing all over Southern California on my blue dream machine. You would be wrong. The next weekend after I thought I was road-worthy Joe and I had a club ride planned. I was all excited to take the R75/5 on its first serious road trip. Come the morning of the ride it would not start for nothing! I ran the battery down, trying all variations of choke/no-choke/throttle/no throttle because I could not believe it wasn’t just about to fire up.

I dumped the fuel in the float bowls. No help. Do I have spark? Yep, pulled a boot, inserted a loose plug, and watched/heard it arc as I cranked (you have to provide a normal spark gap or a short to prevent damaging the Boyer electronic ignition). I pulled the plugs and they looked okay, a bit black-sooty but nothing that didn’t wipe off. Double-checked the gaps. The biggest hint I got was not much smell of gasoline when I pulled the plugs and they were not wet. After cranking that long the plugs should have gotten wet, if not flooded.

Next I messed with both carbs, pulling the jets with the bodies left on the bike. Blew some carb cleaner where I could spray. That didn’t get me started. Hmm, pulled the valve covers and did another complete valve adjustment. They had moved a little since my last check but nothing radical. On a warm afternoon I did get the bike to start again, though it still took some cranking to do it. At this point I double checked the timing. Nope. Perfect. I did away with the points so no gap to check there.

I was SO disappointed as I was forced to mount up on the FJR for the ride. If I recall correctly it was a HOG of Glendale club poker run benefit for Guide Dogs of America. Not the big annual run but just a side run. Still had hundreds of riders show up, final count was something like 400! It ended at the Route 66 Grill in Canyon Country. Those Harley groups know how to party! They had a live band, slow ride contest, beer stein holding contest and more. No pictures. I was too bummed. The R75/5 would have stood out in that ocean of chrome. Yes, Joe won stuff… again. In addition to many raffle prizes (I won some crap) they also had a jar of candy corn and a jar of something else and you had to guess how many in each. Joe guessed closest on both. There had to be two hundred other entries! Can you believe it?

Regarding my R75/5, the only thing I can think of is the Bings have a reputation for difficult cold starting and that morning was the earliest (coldest) attempt I made to date. All my confidence in this machine escaped like air from a balloon. How could I travel anywhere except from-and-to my garage if I was worried I’d run the battery down trying to start it later? Grrrr.

Okay. I was faced with several choices. I could replace some parts in my Bings, maybe even send them out for service since I had several whacks at doing it myself. Or I could replace them with a Mikuni carb conversion that several 5 United members spoke highly of, sold by Stan at Rocky Point Cycle (see link in my big list at upper right). Brad, an old dirt biker, even suggested Mikunis since those were a common swap for Bings back when.

I know in a prior post I said I would not be beaten by my carbs. I was mistaken. I am utterly vanquished by my Bings. But I got even. They’re stored in a box now.

The Mikuni carb conversion cost $375. That is less than just new parts required to attempt to fix my Bings. And owner history on Bings is spotty. Sometimes they work and sometimes they never work. It has to be some manufacturing tolerance issue because it is so widely reported. Not one person complained the Mikunis did not work. They are reported to improve throttle response, ultimate power, and reduce gas mileage. Hey now, THAT’s a tradeoff I can live with! They don’t look perfectly stock but I took photos. Decide for yourself.

Here is the kit from Stan. I broke down and got it this week, taking vacation Friday to get a jump on installation.


It includes two Mikuni VM series carbs (pre-jetted for your application), extra jets (to tune if needed), rubber intake adapters, hose clamps, a length of fuel hose, and custom throttle cables. Very complete! You have to discuss your order with Stan so he can pre-jet correctly and send you the right type of throttle cable. He sells a choke cable conversion also, another $40 IIRC, but I decided to try as is (separate choke levers on each carb) since I can always add it later. Stan developed this conversion to use on his personal motorcycle, a 1971 R75/5, so he has high confidence in the R75 application.

The carbs come stickered “Not for Aircraft Use.” There must be some tiny airplane engines out there if someone might consider using one of these on it? Stan includes a one page instruction sheet and a copy sheet of an exploded carb view but to be honest the instructions are pretty weak. I suppose you could say that if you cannot figure these out you should not be installing ’em. But I struggled slightly anyway.

The first conundrum was “where do the throttle cables go?” The Bings have an external lever that rotates a butterfly. The Mikunis have no butterfly. The throttle cable attaches directly to the main jet’s needle piston through the lid. Here are some views of the carb with the lid off and the guts.



There is also no diaphragm that pulls up on the slide like the Bings, just one big return spring that does double-duty forcing the carb back to idle and also providing the throttle control return force. The float bowl is screwed on, presumably needing to be removed less frequently than the Bing bowl? There are three small brass hose barbs and one big one. The big one was obviously fuel input but what about the other three? Well, one is the carb overflow, something flush-mounted on the Bing body. The other two are vents above the bowl. I’m not sure why two vents are needed but, as confirmed by Brad, don’t block those vents!

Now you know we can’t get through a retrofit like this without monkey-boy showing up somewhere, right? Well, my examination of the carbs led me to think they were two of the same model and lay-out, meaning no left and no right, unlike the Bings. That is not entirely true. Yes most of the body, and for instance the choke lever, is the same on both carbs. But I failed to notice that the idle adjust screw location varied from carb-to-carb. I ended up mounting them with the adjust screws pointed toward the body of the bike, harder to adjust on a hot bike. It was not a complete disaster though because the air mixture screws did NOT vary, meaning one was always going to be harder to access no matter how I mounted them. Strange.

Here is one on the right side of the bike —


Looks okay to me. My only real complaint about the set-up is the custom throttle cable’s length adjusters (to set the 1 mm or so throttle slack on each side) are positioned on the cables so they are hidden under the tank, almost right at my rubber cable loom. It would make more sense to have them exposed on the run of cable between tank and carb.

Yeah, it was annoying to mount up the carbs again. Same twist-dance getting everything on at once. I had a problem with gas leaking at my in-line filters. They were working fine before but now they required tiny hose clamps. Oh well, that’s a hazard of using 1/4″ filters in 7 mm fuel line. One trip to the auto parts store and everything was set right. No new puddles of gas on the floor.

The moment of truth? Rrr, Rrr, Vroom! Started right up. Immediately flipped off the chokes and it idled fine at a slightly open throttle setting. I tweaked idle adjustments so cold idle wouldn’t stall and went for a warm-up ride. It ran just fine up to redline and idle rose after it warmed up. Got it back in the garage, backed off the idle, and tweaked the air/fuel screw on each side for max RPM, keeping idle near 1K RPM. When I was done I took Stan’s advice and turned the screws in a quarter turn (slightly richer) for year-round safe riding. I shut everything off and came in to write up the experience. Took me longer than I thought it would. Call it six hours of work.

I may need to tweak them some more and if I want to balance ’em better than by-ear I’ll have to drill ports for my Carbtune but it seems unlikely I will need to.

So if you see a broken down blue R75/5 on the side of the road somewhere in So Cal, that’s probably me. Happy trails!

September 16, 2007

Bags make it complete

Filed under: 1973, airhead, BMW, BMW motorcycle, motorcycle, motorcycle restoration, R75, R75/5 — Penforhire @ 2:20 pm

So I’m out riding around still doing the whack-a-mole game with mechanical gremlins and I find myself on a major freeway (that’s toll-free highway to you who don’t live in CA). I’m humming along just fine around 65 MPH and I’m starting to relax and take in the scenery. All of a sudden I feel a small thump on my right shin. I look down but I don’t see anything. And everything is still humming along without a glitch. That means nothing off my carb, right? Hmm, large juicy bug? Nope, when I pull over later —


Yep, gorilla snot failure. Well, technically not snot failure. The adhesive is gripping the tank’s paint so fiercely that if I pull on it bits of paint come off with it. I know why this happened. In order to restore my old sun-faded rubber tank panels I soaked them in “Formula 2001” or some similar plastic dressing for months. I tried to protect the backside but I’m sure I failed. So some of this dressing was either on the surface or worked up from inside the rubber and ruined adhesion. I have no idea where, exactly, I lost that panel or I’d go hunting along the freeway. Fortunately these are only $20-something parts and a replacement is on the way from Bob’s.

I’ve only had one really strange thing happen so far. I had fully shifted into second gear after turning a corner on the street. I was then accelerating when the tranny slipped completely into neutral. I don’t know if it was a “false” position or if the neutral indicator was lit. I was too busy throttling down and deciding what to do in traffic with no go. I upshifted and I think I got 3rd gear though I would not bet a large sum on it. Could have been 2nd, I was a touch rattled. But after that shift all was fine. Very strange.

Now that I’m thinking of travelling further on this machine I’m glad my bags arrived. These are semi-replicas of the old Krauser bags, produced today by Hepco & Becker.



They fit onto my stock BMW frames with just a little extra grunting. The right side bag is very tight to the rear turn signal. My right rack loop seems to be shifted to the rear or bent back an 1/4″ or so. This is only significant because the seat will not open completely with the bag in place. I just have to plan on gentle prying each time I want to remove the bag. I say these are semi-replicas because they are better than the originals. They are a little deeper, supposedly will accomodate a full-face helmet, and the latches are improved. There is probably no need to wrap a bungee around them to prevent ’em from flying open on the road.

I had them up to 75 MPH with one bag loaded with about 7 lbs of stuff and no new instability detected. I am very pleased with them. I am the “be prepared” type and that means I feel more secure hauling around a bag or more of crap like tire repair kit, 12 V inflator, flashlight, fuses, full-size tools, first aid kit, GPS, electric jacket liner, water, protein bars, and the like. I know, laugh at me. But I’m usually the guy who pulls out the widget needed to keep me or my riding buddies going.

I added one more long distance touch. I showed you the Throttle Rocker before. While I really like that device, the stock BMW grip length is such that it interferes more with manipulating the front brake than on my FJR. Not only is the FJR grip much longer but I only need a couple of fingers to stop the FJR. I need a full-hand grip to stop the R75. Well, many years of BMW airheads come with a sort of cruise control, a screw with a nylon insert that applies friction to throttle rotation. It is most useful for tune ups or cold warm-up in the garage because it is difficult to manipulate on the move. I stumbled across the perfect solution while searching the 5 United board for distance-riding complaints, the Schneider Flip-a-Lever (see ). It screws in place of the stock set-screw and provides a toggled friction lock, very similar to the Vista Cruise, NEP lock, and similar friction-based cruise controls.


I’m holding the original set-screw for comparison. Here is the lever cammed over into a “lock” position.


The friction applied can be easily overcome with twist of the wrist. There is enough cam that there is zero drag in the “off” position.

I have one more improvement on the way, reduced-strength throttle springs advertised in Airmail (Airhead Beemers Club newsletter). This fellow claims 25-35% reduction in force and for $10 I’m trying ’em. I know my throttle complaint is spring-based because if I twist to full throttle and release the grip it snaps back to idle instantly. This is not a cable or gear friction issue.

My favorite Marsee Rocket 11 liter expanding magnetic tank bag seems to fit fine on the R75. I need the map pocket for route instructions. Joe, are you ready for a Slow Ride (cue Foghat’s music)? There is a new poker run at the end of the month to benefit Guide Dogs of America put on by the Golden State Glendale H.O.G. Chapter (see ). If the hogs can ride it my little R75 can make it!

September 3, 2007


Filed under: /5, 1973, airhead, BMW motorcycle, motorcycle, motorcycle restoration, R75, R75/5 — Penforhire @ 11:51 am

Joe is good. One look at the fork seal photos in my last post and he calls me up, “um, you know those seals are in backwards?” Sigh.

I whip out my Clymers repair and I can’t tell the orientation. Surprisingly, the thin Haynes repair manual is explicit is stating the spring-side goes in first. Could have something to do with that fold-over failure, eh? Monkey-boy strikes again.

Oh well, two fork seal flips coming up. Geez, I just went another 20 miles and everything was feeling right. And it sure is hot in the garage…

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