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Thread: 1973 R75/5 Back-to-road Project

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  1. #1

    1973 R75/5 Back-to-road Project

    I had started another thread "1973 R75/5 Restoration" but brought the bike home today and thought to start over with a more detailed description and some pics. Again, the bike seems unmolested, has set for about 10 years but runs. Here is when I brought it home. Everything works, all the dash lights (although the Neutral lost it's green), all blinkers, horn, high beam, etc. I started it up with no problems. The left carb leaks though, so one of my first things to tackle.

    image1.jpeg

    Also included were many spare parts. Bags with rubber bits and pieces, washers, filters, a brand new ignition switch. Luggage rack, back rest, crash bars (brand new!), side cases from a later year I suppose, a spare header since the original has a dent, Vetter fairing with all hardware, spare gaskets and whatever else you can see in the pic. And now the best, original documentation back to the day the bike was bought. A thick folder with notes, maintenance records and receipts.

    image2.jpeg

    It came with what I believe are original tools! The tire irons have BMW stamped on them. All the wrenches have "Made in Germany" on them and some have the "BMW" on there as well. Original owners manual is included as well.
    image3.jpeg
    Olaf - Austin, TX MOA #200565
    Current bikes: 2012 R1200R Classic, 1973 R75/5 www.R75slash5.com, 1969 CT 70 (108 cc engine)

  2. #2

    More pics

    Left carb is leaking.

    image4.jpeg

    All dash lights work, but the neutral is white, it looks like there is a little green plastic piece that moved out of place.

    image5.jpeg

    Perfectly straight and rust free rims.

    image6.jpeg
    Olaf - Austin, TX MOA #200565
    Current bikes: 2012 R1200R Classic, 1973 R75/5 www.R75slash5.com, 1969 CT 70 (108 cc engine)

  3. #3

    And even more pics

    What do you think about the tank? A bit rusty for my tastes, and there are no fuel filters in the fuel line.

    image9.jpeg

    image8.jpeg

    image7.jpeg
    Olaf - Austin, TX MOA #200565
    Current bikes: 2012 R1200R Classic, 1973 R75/5 www.R75slash5.com, 1969 CT 70 (108 cc engine)

  4. #4
    Registered User kentuvman's Avatar
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    Congrats Olaf - nice ride - I used POR to recondition tank on my airhead.

    You'll more like than likely Ned to buy carb kits from Bing - have you sought out the local airheads club in TX? A great way to learn how to repair, tune and gain appreciation for this wonderful air cooled bike.

    Pretty!
    Ken Tuvman
    Excelsior, MN
    K1200GT & R65LS

  5. #5
    Registered User ebeeby's Avatar
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    A very nice example, again, well done. Looks like perhaps the spokes were upgraded to stainless steel as they are bright - often by this time the zinc has washed off the OEM spokes. This would be a bonus.

    Carb leak could be the float stuck to the bottom of the bowl in the "open" position. Drop both bowls carefully (held in place by "bales") and check bowl bottoms for any crud, clean with carb cleaner, re-assemble and see if leak stops. I would agree that a near-future carb overhaul would be in order and Bing has the the kits. Lots of help available on the internet for this but it can be a bit daunting if you've never done it before. Also, fuel lines get hard/deteriorate and leak where they attach. If I count correctly, there are 10 such connections (without filters). One or more of those may start leaking soon, or, may be the source of your current leak.
    1973 R75/5

  6. #6
    Rally Rat 1074's Avatar
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    Super! The inside of the tank has a red lining that may look like rust. a better test for rust is to stick your finger into the tank and rub it on the inside of the top of the tank. You may feel roughness and pull out your finger with a bit of rust on it. There is a method of removing internal rust without damaging the paint. Spokes look original with a bit of rust starting in the nipple area. Originals are chrome plated. The tool kit bag looks like new! The complete tool kit is pictured in your owners manual. If you can't tell from the picture there are other sources that list exactly what came on the kit. Don't rely on a modern parts book picture such as the one from MAX BMW as a new kit will not have all the original parts. No disrespect for MAX. It's just the parts picture from Germany showing what you get now instead of what you got in 1973.
    Although I do recommend going completely through the carbs to replace all the old rubber parts, there is a possible quick fix for the leak. often you can get a piece of dirt lodged in the float needle. If this is the case you can often flush the dirt out by the following method. Turn off the gas tank taps. Remove the float bowl from the leaking side. Turn a gas tap on for a second to let the fuel flow through the float pin orifice. Push up on the float gently to stop the flow. Repeat if necessary then turn off the tank petcock and put the float bowl back on.
    Boxerbruce

  7. #7
    dharmawheeler
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    Quote Originally Posted by kentuvman View Post
    Congrats Olaf - nice ride - I used POR to recondition tank on my airhead.

    You'll more like than likely Ned to buy carb kits from Bing - have you sought out the local airheads club in TX? A great way to learn how to repair, tune and gain appreciation for this wonderful air cooled bike.

    Pretty!
    I restored the exact same bike but yours looks very clean! One thing I like is that the original rear shocks are on it and not rusty! It is hard to find OEM parts for that.
    Have fun! That Guppie tank is rare. Plus it is the first year that BMW did the extended drive shaft mod and you can see the weld seams. Very cool!



    Sent from my iPhone using Tapatalk

  8. #8
    Thanks 101820, I also really liked the fact that the bike is mostly original, will try to keep it that way!
    Olaf - Austin, TX MOA #200565
    Current bikes: 2012 R1200R Classic, 1973 R75/5 www.R75slash5.com, 1969 CT 70 (108 cc engine)

  9. #9
    Couldn't resist and bought the Conti classics for the looks....hope the ride won't be that bad!

    Another question, are the front pegs supposed to be offset? I can see why, so the clearance to the cylinders stays the same but feels weird to me.


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    Olaf - Austin, TX MOA #200565
    Current bikes: 2012 R1200R Classic, 1973 R75/5 www.R75slash5.com, 1969 CT 70 (108 cc engine)

  10. #10
    Liaison 20774's Avatar
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    After a bit of time, you won't even notice it. Both of my twin cylinder bikes are exactly the same.
    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!

  11. #11
    Rally Rat 1074's Avatar
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    Offset pegs

    True story. When I worked at the dealership we had a customer come back for a warranty problem. Seems the engine was built with the cylinders offset! He was really upset and wanted a new engine.
    Boxerbruce

  12. #12
    Quote Originally Posted by 1074 View Post
    True story. When I worked at the dealership we had a customer come back for a warranty problem. Seems the engine was built with the cylinders offset! He was really upset and wanted a new engine.
    That's a good one! On my R1200R they aren't offset, so that's why I thought there is a mixed set of long/short on my R75
    Olaf - Austin, TX MOA #200565
    Current bikes: 2012 R1200R Classic, 1973 R75/5 www.R75slash5.com, 1969 CT 70 (108 cc engine)

  13. #13

    BIG PROBLEM! Would appreciate your input....

    I started going through things and did the following:

    --Checked compression, both cylinders at 130, from what I read that seems to be good
    --Started on the left side, checked rocker end play, set valve clearances and re-torqued the heads, valve clearances were slightly large but all fine now.

    Now comes the fun part. The rocker arm clearance on the right exhaust valve was too large and I realized that the head bolt from the upper exhaust rocker block was loose (maybe 10 lbs or something like that). I adjusted the clearance, made sure the rocker arm still moved freely over the entire arc and when I tried to re torque the bolt, the stud was pulled out of the engine. I applied not even 15 lbs of torque and as you can see in the pic, the bolt sticks out further than the others.

    Now what to do? I think what I can try is to take the rocker blocks off, tighten two nuts agains each other on the stud and ttry to turn the stud back into the engine case, hoping to catch a thread down there. Now if that doesn't work, what are my options?

    Capture.JPG
    Olaf - Austin, TX MOA #200565
    Current bikes: 2012 R1200R Classic, 1973 R75/5 www.R75slash5.com, 1969 CT 70 (108 cc engine)

  14. #14
    Successfully completed 50 mls test run, I hope I am ready for Harvest Classic next weekend. Is anyone from the area going?


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    Olaf - Austin, TX MOA #200565
    Current bikes: 2012 R1200R Classic, 1973 R75/5 www.R75slash5.com, 1969 CT 70 (108 cc engine)

  15. #15

    Fuelfilter

    Are you running fuel filters on your bikes? I think I need one (or two) at this point, because the bike has sat for so long and I am not sure what's going on deep down inside the tank. I will empty it completely at some point, but not before my next week-end trip to the Harvest Classic (200 mls total).

    I already put 100 mls on the bike with no issues, except that I have a hard time getting all the 14! fuel line connection points leak free. I am using a tiny lawn mower filter since there is no room for anything bigger. I could remove the crossover connection that would help. Does it serve any other purpose than supplying gas to both carbs even if one petcock is clogged up? What is everyone else doing? As always, thanks!
    Olaf - Austin, TX MOA #200565
    Current bikes: 2012 R1200R Classic, 1973 R75/5 www.R75slash5.com, 1969 CT 70 (108 cc engine)

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