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Thread: My 1974 R75/6 story

  1. #1

    My 1974 R75/6 story

    Well, it’s cold, dark, and a little snowy outside right now, so I figured it was time for a write-up of my 1974 R75/6 and my introduction to the BMW motorcycle world.

    Fall 2004
    As mentioned on my R90 thread, I didn’t even know BMW made motorcycles until my friends parents became my new lawncare customer(s), and they had two old, broken motorcycles in their garage under boxes and behind “junk.”



    One of us informed the other that a deal could be made.. and after a small wait, the deal was struck.

    December 2, 2004
    I drove my Blazer to my grandmas to pick up my Silverado/trailer and go pick up my new motorcycle. The Silverado was parked in the field behind the shed because the shed was full of other crap (we'll get to this). I started up the Silverado and drove in a big half-circle before I got completely stuck in the mud.

    So, I:
    went into the shed to retrieve the other trailer inside.
    had to pick up and move about 30 sheets of 4'x8 and 4'x12' drywall that was sitting in the middle of the shed for a different project.
    had to unload approximately 50 computers off of the other trailer.
    had to carry the trailer out to my Blazer.

    This trailer had a single axle, no gate, a license plate that was several years expired, no chains, a questionable wiring harness, and those dinky 12”(?) wheels/tires. Whereas, the stuck-in-the-mud trailer had 2 axles, a gate, clear plates, chains, good wiring, full size wheels/tires.

    I drove out to the customers house. Their son and I determined the motorcycle was too heavy for the both of us to lift. The "ramp" we rigged was a thin piece of plywood, but didn’t work because the R75’s tires were flat. So, we called our friend Jim and his girlfriend to come help. The three of us males were finally able to get it on the trailer, and strap it down.

    I took it by my dads work so that he could admire it (25 years prior, he had a similar year R75/5 toaster tank BMW), and by my jealous friends work for a little bragging. Haha.

    It was getting a little late, and I dropped it off at my grandmas shed and went home to do research. I remember describing the engine to my brother on the phone as looking like a briefcase with cylinders sticking out the sides.

    Winter 2004 / Spring 2005
    I removed the fairing, changed out all the fluids, replaced the battery, coated the tank (with Kreem, yeah, I know), replaced the petcocks, rebuilt the carbs, and cleaned the bike a little bit in the mean time. I also titled it.

    May 16, 2005
    I was hanging out at my grandmas with my brother when his friend Mark stopped by and after some prodding, he convinced me to drive home and get the gas tank that I had waxed. I brought it back, and after a very small amount of effort, I had it running for the first time. This machine sat for 20some years with gas still in the tank, and it's able to start up with very little actual mechanical work. I put 12.8 miles on it riding it around the neighborhoods near my grandmas.

    The following year

    I rebuilt the master cylinder. I bought the appropriate headlight parts and turn signals along with a few special tools. I sold my fairing. I did general work on cleaning and maintaining the bike.

    August 26, 2006
    As I was pulling into my driveway, the motorcycle died. I attempted to restart it, but the only thing that happened was the blinker blinked once, and quickly dimmed out.

    Afterwords,
    • there was no response from the starter button,
    • the neutral light did not work,
    • the blinkers wouldn’t do anything more than flash once,

    I did the following to troubleshoot the problem;
    • I replaced the starter relay with a brand new one, but nothing changed, so I re-installed the old relay.
    • I replaced the fuses with new ones, but nothing changed, so I re-installed the old fuses.
    • I tried to charge the dead battery with a charger that was supposedly “too powerful,” and may have “fried” the battery.

    Of course the day that happened, both my mom and my grandma asked "Oh, you got the motorcycle running?"

    It sat in this condition for a little too long before I was fed up with troubleshooting, and decided to take it to a shop. In this time I finally got a digital camera. Here is a picture of how it was as of about the beginning of August 2006.



    This is about 50x better than it was when I recieved it. Yet, notice:
    the Vetter Windjammer wiring harness just hanging out of the bottom of the headlight.
    the semi-bent posts where turn signals should be.
    the shredded fork gaitors.
    the rust all over and the dirt.
    the rusty/green spokes.
    the tires:


    November 9, 2006
    Iit passed inspection.

    November 13, 2006
    Icensed it.

    Mid-December, 2006
    About 1000 miles accumulated.

    May 4, 2007
    I'd ridden it about 2000 miles. I changed the oil and filter in 'er.. a little premature, but I wanted to examine if there were any metal shavings in the oil. None.

    July 14, 2007
    First several-hundred mile road trip. Stopped at my family farm for fireworks.



    September 2007
    Installed new carb floats and removed dried/cracked fuel filters.

    Early October 2007
    Attended the Falling Leaf rally in Potosi, MO.



    October 20, 2007
    Rebuilt the speedometer.



    October 21, 2007
    Speedometer cable broke, so I replaced it. I swear it had nothing to do with my rebuild! Haha.



    October 28, 2007
    It wouldn't freaking start that morning. So, I adjusted the R75 valves with my new metric feeler gagues and set the clearances as per the Clymer. As they were, one intake was probably 1.5+mm, the other was slightly less, and neither exhaust valves actually closed. Ridiculous. Surprising it even ran. I also noticed the carbs were a bit cockeyed, so I made them more vertical, and made sure all the connections were tight. The ride home was like a whole new bike. Amazing difference in performance.

    December 4, 2007
    It happens to everyone. I dropped it. At least this was in my front yard. Left a funny valve cover dent in the ground.


  2. #2
    December 5, 2007
    I rode to school in the freezing rain, as I had been doing the past few days. I went to leave, and I got nothing but "ticktick" and a dead battery. My professor that I had that day walked by and I asked him if he had jumper cables. He acted like he didn't know me, and told me to contact campus security. I got them to bring me 3 different battery chargers‘«™. and nothing. I called my friend Matt to come pick me up. So, when I was waiting, I attempted to pop-start my motorcycle in the parking lot. Twice I forgot to turn the key on. The last two times, it fired a couple times, but failed to get running. After Matt arrived, a very good looking girl pulled up and asked if we needed help. She thought it was Matt's car that had the trouble, but I explained it was my motorcycle. She said "Well, if you need anything, let me know." And she drove off. Neither of us know/knew her. Matt took me home. I got my truck and went to my grandmas to pick up my trailer. I picked up the bike, and put it in the shed there. I spent the rest of the day trouble shooting

    December 25, 2007
    I hooked the battery charger directly to the starter, with the same results. Just ticking. I took the starter off, and hot-wired it with the battery charger, and it spun freely. I took the starter off my R90 and hot-wired it with the battery charger also. It acted the same as the R75 starter. It spun right along. So, I figured I'd just go for it, and hooked the R90 starter up to the R75. I hooked the charger directly to the starter. It ticked just like the R75 starter did.



    January 5, 2008
    I had some spare parts laying around, so I hooked up a new/good starter relay and the ticking continued, but it "caught" a couple times and you could hear it blup blup as each cylinder slowly turned over, but it went back to ticking.

    Winter 2008
    I had a list of things to do to the bike and accomplished a few of them, except getting it to start. I couldn‘«÷t figure it out. I just couldn‘«÷t bring myself to buying a new battery, especially knowing that the battery charger was good.

    March 8, 2008
    Forum member woodnsteel decided to come to my aide. He made the trip from Peoria, Illinois to our shop in Missouri (195 miles!).



    In preparation for this, I bought a new battery (although I previously thought mine was good), rings, and a few other things. We gave my bike a spline lube, honed the cylinders, installed new piston rings, installed new push rod tube seals, anti-seized the exhaust nuts, and installed the new battery. The bike ran A-OK again.

    March 11, 2008
    Well, my push rod tube seals were cheap after-market ones, and 3 of the 4 split, so I replaced them. I also adjusted the valves.



    Summer 2008
    Fluid changes, etc. Installed new oil pressure switch because it was leaking pretty bad.



    July 17/20, 2008
    I attempted to take the R75 to the MOA national rally. In Western Iowa, a storm rolled in. I took refuge at an abandoned gas station for a while, before heading back out in it.



    After ‘«£sleeping‘«ō under a picnic table at a rest area in a heavy rainstorm, I got stranded in Nebraska during the second day of the trip due to a faulty charging system (a rotor wire cracked) and had to abort the mission. A fellow in Council Bluffs, and a family in Omaha came to my rescue and helped me along my journey. BMW Omaha was absolutely helpless/worthless, and after wasting a few hours waiting there, I told them to forget it, and I‘«÷d be on my way. I have a lot to say about this trip, if anyone‘«÷s interested. It was ridiculous.

    Fall 2008
    I plugged my bike in every night, and could only go on rides of less than 200 miles before I‘«÷d start having trouble. One such ride was in a snowstorm in rural Missouri, where a priest at a gas station most likely saved my life after my headlight and taillight had all faded away. That sucked. I bought a new diode board, as was recommended, but still had no luck.
    I moved to finish off my school career. My brother used my truck for lawncare back home, and I parked my motorcycle in my new living room. As evidenced by the bare walls and lack of tv/computer, I am a party animal! Haha.



    It gave me time to just sit there and stare at the ol‘«÷ girl.



    Also, my carb diaphragms developed a small tear and after some troubleshooting, I replaced them, and was able to reach speeds above 65 again. Hallelujah!
    I bought a large /6 tank online (a little more rough than advertised if I do say so) and installed it.

    Also, went on my first group ride. Not as scary as I was thinking.
    Rebuilt my speedometer again, as a gear had slipped on its shaft.



    ..and this little guy migrated.



    Of the ONE time I didn‘«÷t have any extra ropes/bungee cables, my left Krauser decided to abandon ship. Shortly thereafter, as I was standing on the side of the road waiting to snag it from traffic, it was obliterated by some target-fixated moron in a blue car. Everything in it was killed, including my camera and ipod. This is what was left of it.



    October 10/12, 2008
    Attended my second Falling Leaf Rally. This time, I actually had enough time to camp.



    Winter 2008
    woodnsteel to the rescue again. He graciously made the trip again with spare parts in hand. He showed me many charging system diagnostics, and when it came time to test the rotor, we found the culprit. One wire inside had broken, and it wasn‘«÷t charging my battery back up. Replaced it, charging light went off, and it has run fine since then.

    I ‘«£machined and installed some high performance parts.‘«ō





    Spring/Summer 2009
    She treated me well. She just wanted to ride. So, ride we did.



    I rode my R90 quite a lot at this time (including to the national), and my R75 got jealous. So, during a back way ride from my moms house to my house (~150 miles), as I got out into no-mans-land, a small o-ring in my left carb came apart. I was honestly so confident in this bike by now, I didn‘«÷t bring tools with me on this trip. Big mistake. The bike was running so poorly, I probably could have gotten off and pushed it up the hills I was riding. I didn‘«÷t know what the problem was, but as I had just replaced my sparkplugs, I thought it might have something to do with them.

    I stopped at a gas station, no tools. The bar next door; ‘«£Do you have any tools here?‘«ō ‘«£Sure, what do you need?‘«ō ‘«£Spark plug socket.‘«ō ‘«£Oh, no, we don‘«÷t have anything special like that.‘«ō A patron offered to let me go to his shop. I was very thankful, and suited up to follow him. As he got in his truck, he yelled ‘«£GREAT, JUST WHAT I WANTED TO DO ON A SUNDAY NIGHT!‘«ō I followed him there, and apologized for going so slow, and he said ‘«£Yeah, I thought I was going to have to throw it in reverse.‘«ō Um, ok. I adjusted my valves and gapped the plugs, and it ran like a top.

    A few minutes down the road, it went back to crap. The 2.5 hour ride took 6 hours. The bike died 3 times. After dark, the fog started. I couldn‘«÷t even see my feet or the road. The next day, now that I was at home, I found and fixed the problem in 15 minutes. She‘«÷s back runnin‘«÷ fine and treating me well.

    Winter 2009
    Still ridin‘«÷.







    The left kneepad was coming off, so I yanked it off to not lose it.
    I think I‘«÷m going to do a rear main seal/oil pump o-ring in the next week. I‘«÷d like to repaint the large tank, as the paint on it sucks (dull gas stained black spray paint over original blue).

  3. #3
    habdala
    Guest

    Patent

    You should patent that.


  4. #4
    Registered User ebeeby's Avatar
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    McKinney, Texas
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    Great story, great photos , thanks for taking the time to post it all.
    1973 R75/5

  5. #5
    --Tony AnnapolisAirhead's Avatar
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    Watkinsville, Georgia/Annapolis, Maryland
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    1,801
    Nathan, yours is a great, great story of patience, perseverance and tolerance (in terms of the valves, carbs, and yours). Its amazing how much these bikes can take.

    Love the fireworks picture. Nice eye.
    1971 BMW R75/5 | 1975 Moto Guzzi 850T Cafe | 1983 BMW R100RS | 1988 BMW R100GS
    1988 BMW K75 | 1998 BWM R1100RT | 2000 Moto Guzzi Quota 1100ES |2002 Moto Guzzi V11 LeMans

  6. #6
    Liaison 20774's Avatar
    Join Date
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    San Antonio, TX
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    Not the least of which is to take the time to post this and keep us up to speed. That takes away from ridin' and wrenchin', but from what I hear is going on at the St. Louis area, it's too cold to be doing anything other than sitting inside hitting the keyboard!!
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  7. #7
    I plugged my bike in every night, and could only go on rides of less than 200 miles before I‘«÷d start having trouble. One such ride was in a snowstorm in rural Missouri, where a priest at a gas station most likely saved my life after my headlight and taillight had all faded away. That sucked. I bought a new diode board, as was recommended, but still had no luck.
    what did you wind up doing to fix the problem, my r90 just developed the headlight disappearing feature (the bike still starts and runs) and I can't diagnose it
    // 1975 BMW R90/6 (cafe'd) // 1957 BMW R60 (in pieces) // 1967 Aermacchi/H-D Sprint 250 SS (custom special) // 1967 Moto Guzzi V700 (current restoration)

    http://symphonyofshrapnel.blogspot.com

  8. #8
    Quote Originally Posted by 20774 View Post
    St. Louis area, it's too cold to be doing anything other than sitting inside hitting the keyboard!!
    Haha, yep. I've ridden in some cold stuff, but really, when I don't have anywhere to be, it's not worth the time it takes to put on the 20 layers.

    Quote Originally Posted by Typ181R90 View Post
    what did you wind up doing to fix the problem, my r90 just developed the headlight disappearing feature (the bike still starts and runs) and I can't diagnose it
    In this case, it was the rotor. A wire on it broke,alienating the slip rings, thus eliminating charging. Same thing happened to my R90.

    The symptoms included: constant half-intensity GEN light, diminishing lights on the ride, eventual sputtering, and finally a backfire, and the bike would die. Not to be started again without assistance. Then, more than a full day back on the charger, and the scenario would start again... when I actually let it get this bad, I was in Omaha, and didn't really know of the problem. Since then, I've seen countless records of it, and am absolutely blown away that BMW Omaha had no idea how to diagnose/test for it. They eventually offered to disconnect all my lights, but I told them to forget it. They didn't even know that one of the airheads key positions is "light-less", if you will. After hours of waiting, I just decided to go home.

    Think of it simply; a charged battery that's getting drained. Every little load on it is sucking its life away. Lights get dim, and it can no longer spark. Then, you're stuck.

    Of what little I've read from your description, it doesn't sound like this (rotor) is your problem, but if you want to elaborate, we're here to help..

  9. #9
    Quote Originally Posted by crazydrummerdude View Post
    In this case, it was the rotor. A wire on it broke,alienating the slip rings, thus eliminating charging. Same thing happened to my R90.

    The symptoms included: constant half-intensity GEN light, diminishing lights on the ride, eventual sputtering, and finally a backfire, and the bike would die. Not to be started again without assistance. Then, more than a full day back on the charger, and the scenario would start again... when I actually let it get this bad, I was in Omaha, and didn't really know of the problem. Since then, I've seen countless records of it, and am absolutely blown away that BMW Omaha had no idea how to diagnose/test for it. They eventually offered to disconnect all my lights, but I told them to forget it. They didn't even know that one of the airheads key positions is "light-less", if you will. After hours of waiting, I just decided to go home.

    Think of it simply; a charged battery that's getting drained. Every little load on it is sucking its life away. Lights get dim, and it can no longer spark. Then, you're stuck.

    Of what little I've read from your description, it doesn't sound like this (rotor) is your problem, but if you want to elaborate, we're here to help..
    My situation isn't as bad as yours was, I have no problem starting the bike or while riding other than the headlight seems to dim at stops (gen light never comes on and the headlight comes back on most of the time with a quick rev, but sometimes stays off). The taillight and signals will still work while the headlight is out and if I turn the bike off and turn it back on the headlight will come on. Charged the battery and problem still exists, went through the wiring and everything looks good. Was thinking about upgrading the alternator to an Enduralast or an Omega just for the sake of upgrading but maybe that'll help give it that extra charge at idle/low speeds to keep it lit.
    // 1975 BMW R90/6 (cafe'd) // 1957 BMW R60 (in pieces) // 1967 Aermacchi/H-D Sprint 250 SS (custom special) // 1967 Moto Guzzi V700 (current restoration)

    http://symphonyofshrapnel.blogspot.com

  10. #10
    btw everytime I put the battery on the battery tender it always immediately goes to 80% so I don't think my battery is being discharged that much
    // 1975 BMW R90/6 (cafe'd) // 1957 BMW R60 (in pieces) // 1967 Aermacchi/H-D Sprint 250 SS (custom special) // 1967 Moto Guzzi V700 (current restoration)

    http://symphonyofshrapnel.blogspot.com

  11. #11
    rocketman
    Guest
    Quote Originally Posted by Typ181R90 View Post
    My situation isn't as bad as yours was, I have no problem starting the bike or while riding other than the headlight seems to dim at stops (gen light never comes on and the headlight comes back on most of the time with a quick rev, but sometimes stays off). The taillight and signals will still work while the headlight is out and if I turn the bike off and turn it back on the headlight will come on. Charged the battery and problem still exists, went through the wiring and everything looks good. Was thinking about upgrading the alternator to an Enduralast or an Omega just for the sake of upgrading but maybe that'll help give it that extra charge at idle/low speeds to keep it lit.

    for a 1975 Not having the Gen light come would seem to indicate a problem, unless your idle is over 15-1600 RPM's it should be coming on and the headlight should also dim a bit when at idle which should be around 800-1000 RPM's, any higher than that could lead to overheating in summer stop-and-go. Also if I remember correctly the Gen light acts as a resistor in the starting circuit and if non-functional can cause starting problems, but maybe that was just the /5’s? Also as long as you are moving with bike fully in gear, you doing at least 2000-2500 RPM's and should be giving the battery a good charge, discharing problems related to speed would be when Not moving or so slowly you're having to constantly work the clutch (i.e. idling for extended periods esp, with any extra lighting or loads). The fact it dies then come back on when you rev it or cycle the key would lead me to think of short/lose connection somewhere, possibly a relay (headlight) or key switch or the headlight blub or holder itself, that has not yet failed but could down the road. Something more than a visual check might be in order, try testing connections by grasping the wires, wiggling the key or running a meter while doing the above. I've had times when the wires all looked good, but the connections were at fault sometimes right at the spade connector or corrosion inside the connections not obvious from the outside. But whatever it is I’d do some more checking and find the problem if at all possible.

    RM

  12. #12
    rocketman
    Guest
    Quote Originally Posted by Typ181R90 View Post
    btw everytime I put the battery on the battery tender it always immediately goes to 80% so I don't think my battery is being discharged that much
    if the gen light never comes on then yes, the battery should remain pretty well charged, dimming of headlight if nothing else dims is most likely not battery related.

    RM

  13. #13
    Quote Originally Posted by rocketman View Post
    for a 1975 Not having the Gen light come would seem to indicate a problem, unless your idle is over 15-1600 RPM's it should be coming on and the headlight should also dim a bit when at idle which should be around 800-1000 RPM's, any higher than that could lead to overheating in summer stop-and-go. Also if I remember correctly the Gen light acts as a resistor in the starting circuit and if non-functional can cause starting problems, but maybe that was just the /5‘«÷s? Also as long as you are moving with bike fully in gear, you doing at least 2000-2500 RPM's and should be giving the battery a good charge, discharing problems related to speed would be when Not moving or so slowly you're having to constantly work the clutch (i.e. idling for extended periods esp, with any extra lighting or loads). The fact it dies then come back on when you rev it or cycle the key would lead me to think of short/lose connection somewhere, possibly a relay (headlight) or key switch or the headlight blub or holder itself, that has not yet failed but could down the road. Something more than a visual check might be in order, try testing connections by grasping the wires, wiggling the key or running a meter while doing the above. I've had times when the wires all looked good, but the connections were at fault sometimes right at the spade connector or corrosion inside the connections not obvious from the outside. But whatever it is I‘«÷d do some more checking and find the problem if at all possible.

    RM

    I should have clarified, my Gen light works, but at normal speeds it disappears. I'll def. take your advice and go deeper than a visual inspection on the connections
    // 1975 BMW R90/6 (cafe'd) // 1957 BMW R60 (in pieces) // 1967 Aermacchi/H-D Sprint 250 SS (custom special) // 1967 Moto Guzzi V700 (current restoration)

    http://symphonyofshrapnel.blogspot.com

  14. #14
    rocketman
    Guest
    Quote Originally Posted by Typ181R90 View Post
    I should have clarified, my Gen light works, but at normal speeds it disappears. I'll def. take your advice and go deeper than a visual inspection on the connections
    Ok, that is a good thing, then. Finding the source of such problems can be a PITA, I had an intermittent shorting/engine just totally dying/all lighting and spark just going bye bye off and on during what Should have been a nice three day ride out in the middle of nowhere WV last year, just kept hoping it would get me home or at least back to someplace with actual residents and such other than bears, birds and bees. .kinda took the thrill of purposely getting lost in the backwoods on a reliable machine. It would start right up as soon as i pulled over sometimes turning the key on and off, sometimes just lighting back right away as soon as I hit the starter...
    then it stopped for several weeks, then happened again on another ride, each time I looked and looked..but nothing seemed out of place.. then it happened a third time just as I was going into a turn then fired right back up as soon as I started to pull over.... sat thinking.... Hmmmm started wiggling the wires leading to the handlebar switches, sure enough they had pulled out just enough to short the kill switch wires on the handlebars but not enough to be able to see it. Talk about a major relief, nothing worse that Not knowing what the problem is and always having that possibility sitting in the back of your mind can be a real Kill-joy!

    30 year old wiring can be tricky, you could have a broken/almost broken wire inside the insulation and never see it till you start jiggling it, looking for places along the backbone where the wire insulation looks slightly fattened can sometime point to problems, using a good bright flashlight can help, I used some contact cleaner sprayed on my old grungy wiring along the backbone to clean it up to see it better when tracing my last problem and replaced any connection that even looked suspicious. I found the peace of mind was worth the effort. (but I Still carry wiring, tape and spades and splices and crimping tool in my spares kit!)


    RM

  15. #15
    wandering
    Guest
    great story drummer. dig your photography and beemer posts out here on the www.

    nice milk-jug-busters?ę

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