I bit the bullet. 1974 r75/6

Discussion in 'Old's Cool' started by squirrelscoundrel, Nov 11, 2009.

  1. squirrelscoundrel

    squirrelscoundrel beginner metal jockey

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    Fabulous Rhode Island
    I bit the bullet and picked up the r75/6 I have been drooling over and dreaming about (literally) for weeks. The plan is to take the aquamarine bike that has been sitting for a few years and could use some help into a unique, mechanically perfect bike. I am not sure that I am going to do the cafe thing, nor will I be cutting the frame, and definately do not have the funds to make it original. I managed to get the bike for 700 bucks, and upon bringing it home hooked it up to my car's battery and despite being off the road for 4 or 5 years, it fired up and I rode it in the driveway.

    I was warned by the previous owner that the 4th gear is non operational, so mechanically, that absolutely must be addressed. I am also going to take the motor apart for a good cleaning and make sure that everything in OK. Carbs cleaning, etc as well. It is going to need new tires, mirrors, front blinkers, a sidestand, and an overhaul on the brakes, as well as making sure the driveshaft is in good shape. My plan is to have this baby purdy and purring by the spring.

    As I am a teacher at a boarding school, I have enlisted the help of some interested students and will be offering the "restoration" of the bike as an afterschool club. The paint scheme is in the air, but will be likely be some combination of black, red, and white, the school's colors. I really do not know much about mechanics, but a few of the students are knowledgeable, so I guess we'll all be learning together. I am extremely excited to begin a new project. I will be keeping all posted as to the progress of the project and I am sure that I will have more than a few questions.

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    #1
  2. Wirespokes

    Wirespokes Beemerholics Anonymous

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    I'm a firm believer in not fixing something that aint broke. By all means check the oil pressure, do a compression check, leak down test or any other checks you can think of; only then if they indicate a problem tear into it.

    Pull the heads and clean out the carbon and replace the pushrod seals. At the same time, pull the lifters and inspect for pitting and corrosion. Check the cam at the same time by looking into the empty lifter holes. The cams can sometimes be pitted and worn down.

    I'm with you on changing the color - what were they thinking???:puke1

    Hope you got a box of parts with it - like a headlight and the front turn signals!

    And, as for the trans, I'd suggest finding a good used one, something newer, one build closer to 1980.
    #2
  3. squirrelscoundrel

    squirrelscoundrel beginner metal jockey

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    I do have the headlight, but no for blinkers. The engine is leaking oil out of the bottom so I am expecting to install new seals while she is all apart.
    #3
  4. squirrelscoundrel

    squirrelscoundrel beginner metal jockey

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    I do have the headlight, but no for blinkers. The engine is leaking oil out of the bottom so I am expecting to install new seals while she is all apart.
    #4
  5. bgoodsoil

    bgoodsoil Dare to be Stupid

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    +1 on what Wirespokes said. Buying a spare transmission will be much much cheaper than getting that one fixed. check the marketplace on ibmwr.org. Gearboxes can be swapped from many different bikes. Anybody know any specifics on the swapability between models? A good used gearbox will probably run you around $400

    There's a guy on here named Infracaninophile (no idea what that means) and he does incredible write-ups on maintenance. His thread'll walk you through valve adjustments, oil changes and rebuilding the carbs.

    http://www.advrider.com/forums/showthread.php?t=431153&page=8

    if you can get us pics of the leak we can tell what you need and part numbers

    you can find any part you need here. it's OEM so it's often expensive. It's good for seals and cables and such though.

    http://www.maxbmwmotorcycles.com/fiche/fiche.asp

    that bike should have hypoid gear oil in the gearbox, the driveshaft AND the final drive. I've seen some destroyed final drives because somebody forgot to fill the oil in it. 80W-90 or 75W-90 is what most folks run. Castrol GTX 20w-50 from autozone will be fine for the engine. You don't need a special motorcycle oil for an airhead.

    here's a write-up on the pushrod seals that Wirespokes was talking about:

    http://www.gunsmoke.com/motorcycling/r100gs/pushrod_tubes/index.html

    There's a group called the Airheads Beemer Club, the ABC. If you get in a bind go to http://www.airheads.org and see if anyone's offering a tech day in your area. You might be able to find someone local that can give you some pointers.

    I'd start with this: get a new battery, change all the fluids and see how she runs.

    I wholeheartedly recommend a maintenance free battery like an Odyssey. 80% of motorcycle breakdowns are from dead batteries.
    #5
  6. norton73

    norton73 drinkin'

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    the colour is definitely unique
    #6
  7. squirrelscoundrel

    squirrelscoundrel beginner metal jockey

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    Thanks for all of the good info and advice. I will keep all posted with progress (is using the P word too optimistic?)
    #7
  8. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Any of the transmissions without ribbed cases will fit your bike without any modifications. Stay away from a 74 or 75 trans since key new parts are no longer available for them. One gear may need replacing, but would require upgrading half the box to get it in there. Not worth the trouble!

    That's good you got the headlight! Now start watching for the turn signals - usually about $25 each. Or I think Bob's BMW sells them, or maybe even Vech at Benchmark Works. Maybe Blue Moon...

    When these bikes sit idle for any amount of time they start to leak. Ride them regularly and they stay dry, unless a seal has gone bad. With a long-parked bike expect to replace some seals. The thing to do is clean it all up well, then ride to see what's leaking. Ride some more... and perhaps it'll stop leaking. If it doesn't, replace the seal or gasket. And take it easy on the pan bolts! They're small and over-torquing will strip the threads in the block. If you've tightened them down pretty snug and still leaks, either replace the gasket or use something like non hardening aircraft gasket seal to stop the flow.
    #8
  9. cheesebot

    cheesebot I cheesebot

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    Was this the bike listed in Bristol for $1000? If so it looks like you got a pretty good deal. I had to keep making excuses to myself for not calling the guy and spend more time repairing my /5. The last thing I need is another project...
    #9
  10. squirrelscoundrel

    squirrelscoundrel beginner metal jockey

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    Yeah. That was the bike.
    #10
  11. dragoon

    dragoon I'm the REAL Dingo Joe

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    or, she has a great personality:lol3
    #11
  12. spo123

    spo123 Man About Town

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    I passed that ad along to my son and a buddy at work.......Glad someone worthy got a good deal!:beer
    Good Luck and Ride Safe!:gerg
    spo:jose
    #12
  13. norton73

    norton73 drinkin'

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    :rofl
    #13
  14. Dabears

    Dabears Long Timer

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    You know, it's almost a blessing that it's the color it is. Now you don't have to fret about whether you should just try and polish it up with the existing paint. I can think of several colors that would look great on it- aquamarine blue isn't one of them!

    Have fun on your project. I hope you'll share the progress with us.
    #14
  15. crazydrummerdude

    crazydrummerdude Wacky Bongo Boy

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    A 1974 R75/6; my intro to airheads/BMW's.

    Be sure to post lots of pics.
    #15
  16. squirrelscoundrel

    squirrelscoundrel beginner metal jockey

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    I have not yet started to take the old girl apart, but I pumped the tires up a bit and took it for a spin in the driveway. I wanted to test the 4th gear as I was told when I bought it that the 4th gear did not work and that it might be a shifting fork. When I kicked it into 4th, there was no grinding or noise, but it just felt like a neutral. I know that the problem can not be diagnosed until the transmission is apart, but does my description sound like a busted shifting fork? something else? Ideally, I would rather fix the existing transmission than to just buy a new one and bolt it on. If it is indeed a fautly shifting fork, it is going to be a great deal cheaper than a new transmission and I will learn more about transmissions by taking it apart, fixing it and putting it back together. Is it unrealistic to think that I, being previously not particularly mechanically inclined can fix a hurting transmission?

    I was riding at dusk and after letting the bike warm up for a few minutes, I looked down and the downpipe from the left cylinder was red hot. Is this normal? The bike seemed to be running fine, but Red Hot?!!? that seems a bit extreme. After putting it away, I realized that I have never checked the oil level and have no idea if it is full, or very low, or if there even is any. I am going to start the project in ernest the tuesday after thanksgiving. I have a bunch of students intersted (maybe too many) and am pretty excited to get the party started.

    Thanks for the info.

    Also does such a thing exist as a kit with all of the appropriate seals and gaskets for the engine? While it is apart, I am going to want to replace them all and just want to know the best and easiest way to find the parts.

    Thanks for all of the support and advice so far. I would not feel comfortable getting into a project like this without the support and expertise of those who have gone before me.

    Doug
    #16
  17. bpeckm

    bpeckm Grin!

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    I would be very leary of getting into the transmission... that is ONE place where precision is really necessary! And it isn't an easy thing to just open it up... on the other hand, if 4th gear is kerflooey, what can you lose? You can buy a used tranny all day for $3-400, and rebuilding one would cost far more than that.....

    Re: seals kits, etc, check out Hucky's Spare Parts. He will advise, and put together a custom "kit" of seals if the website grouping doesn't fit. A Good Man to help with advice, parts; service is excellent, and his website is a help when you are looking for parts.... he has pictures!

    Red-hot downpipe! Not good!.... the usual suspect is an air leak, meaning that it is running super-lean, drawing in extra air and burning super hot. Check for vacuum leaks on the intake, and make sure that the exhaust is clamped on tightly.....Vacuum leak test: start the bike, and at idle squirt some WD40 around the area between the carb and the head, if the engine speeds up, it is sucking in the WD and using it as extra "fuel"... tighten all the connections!

    :D
    #17
  18. Wirespokes

    Wirespokes Beemerholics Anonymous

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    I believe the glowing header to be too rich a mixture which is still burning in the pipe.

    Like bpeckm said, transmissions aren't something to fool with. They require several special tools and considerable mechanical knowledge. It's not a job for a newbie. Even an excellent mechanic who isn't all that experienced in these transmissions can have a tough time. Working on these things is half high tech and half black art. It takes having a 'feel' for them that can only be gained by experience.

    I'd suggest connecting to the airhead beemer club and getting to know some of the better mechanics in your area. Perhaps one of them would be interested in helping you sort it out.

    I'm thinking the shift dogs might be sheared off of fourth gear if everything felt normal shifting into gear. Drain the trans oil for us and show us what you find. Drag a magnet around in there to snag any steel bits that might not have flowed out with the oil.
    #18
  19. spo123

    spo123 Man About Town

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    The cherry red exhaust pipe(s) are most likely from you allowing the bike to warm up for TOO LONG.
    spo:gerg
    #19
  20. bmwhacker

    bmwhacker Still on 3 wheels

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    I purchased your new bikes twin sister a couple of years ago, for the same price too......although she was an R90.....I concur with the opinions on the 74 & 75 transmissions...I will run mine until it dies and swap for a newer one or go to the earlier 4 speed which is better (IMO) for sidecar use........The bike was sacrificed as there were too many issues which made it a total money pit to restore...the engine top end lives on my R75/5 along with the sidecar......The " inheretly weak" 1974 5 speed tranny is now living on a 1000cc "tug" project...I have doubts it will survive long coupled to a 1000cc engine......


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    #20