Back on an Airhead - 1975 BMW R90/6

Discussion in 'Airheads' started by tete, Aug 27, 2012.

  1. tete

    tete clown shoes

    Joined:
    Oct 15, 2009
    Oddometer:
    346
    Location:
    Gilbert Az
    So after owning a 81 R65 a few years back, and 4 hondas in between i got my hands on a 1975 R90/6 Monza Blue. I got what I believe is a smoking deal, but of course it was sitting for a bit and will require the usual paces to get her going. It was parked in 2001 gue to a faulty starter. Im sure the battery is rubbish. It was stored in a garage here in Az. The tires are surprisingly good still and it was leaking oil at some spots which is to be expected since it hasnt moved for a decade ( very little oil ).

    I hooked up some juice to it and all the lights etc worked. Im chargin the battery overnight to see if there is anything left to give simply for testing.

    The bike came with alot of exta stuff.
    new seat pan off what looks to be off an RS model - very cafe like.
    a larger capacity tank
    A fairing - bullet like - not the big cobra kind.
    new mirrors
    some shocks that look to be off a higher RS model
    Also fender both front and back.

    Im pretty excited about getting it going. so here a few things that I'm concerned about first.

    What is general " process for bring a bike from state of storage - ten years sitting.

    This is my initial plan:

    Change engine oil, plugs -
    rebuild clean carbs -
    find a starter - which is a good brand? Im on a budget because I just had my 3rd boy. Diapers take priority
    also souce a new Gel battery as if I recall my R65 would use up alot of juice.

    please if you have nay advice you WANT to give me please do. Till then I will use the search function and learn as much as I can about my new bike.

    [​IMG]
    #1
  2. disston

    disston ShadeTreeExpert

    Joined:
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    Oddometer:
    10,412
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    Silver Spring, Md
    Before you condemn the starter put the fresh battery in it and clean all the wiring. See how much juice is getting to the starter through the relay.

    The '75 models were the 8 tooth verity of the Bosch starter. In '77 they went with 9 tooth. The two don't mix. Your starter matches the gear teeth on the flywheel. So if you go with another starter it has to be 8 teeth. But there is the option of rebuilding that starter and to my mind the way to go. Rebuild parts are readily available or you could have it done for you at an Old Timey Auto Electric Shop. They are getting harder to find but do still exist. And if you are handy at all you can do the rebuild yourself.

    I say rebuild parts are available. If the suspect starter has any major defect like a bad rotor or stator or coils or what ever it gets more complicated.

    So then more modern starters are available.

    Find any number of battery threads in the last two weeks. I think AGM batteries are popular. Maybe somebody will mention a particular one. You can make a smaller battery fit. The 22 AH UB12220 works for some. The stock BMW battery is very expensive again. I think this year around $129 over the counter. The battery in your bike is the wet cell OEM battery.

    The rest of your plan sounds good. Rinse the gas tank out well and clean the petcocks. Replace the fuel line. Even if it looks good right now it is going to start leaking almost immediately.

    The stock attachment for the battery covers, those triangular things on the side, are a rubber band. It will break and you will loose the right side battery cover. They are hard to come by cheap. If all you have holding those covers on is the rubber band then put the right cover, the left one won't fall off, in the house until you make a more secure attachment, usually drilling a hole and wire tying it to the frame.

    Some riders like that color.

    Welcome to the Asylum.

    I ride a 1975 R90/6 Black

    ps, there area of the engine block right behind the front cover is the timing cover. About two inches wide. It looks chrome plated in the picture. Is it just polished? Then somebody did a timing chain on this bike?
    #2
  3. tete

    tete clown shoes

    Joined:
    Oct 15, 2009
    Oddometer:
    346
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    Gilbert Az
    Thanks for all the info!

    First bit is to get a good battery. Perhaps a decent but inexpensive battery and a tender is the way to go.

    I have been tryin to use the search function to find what process to go thru in regarding oils. It's is my understanding, that these bike need oil in several spots. or as many as five? I hope that perhaps its some the the wiring of the starter as I read that goes bad pretty quickly, but it is my impression that the PO was pretty well informed with the bike. He's dead now, unfortunately, and his son, had no idea what he was even looking at.

    He also mentioned an alternator? I don't think he had a clue but maybe Im really the fool.

    The motor does have a chrome / polished strip. You mentioned a chain, perhaps you can be a bit more specific if you don't mind.

    and finally, where can I source a OEM seat cover or a company that makes a high quality replica.

    In some ways all the information here is a double edge sword as when using the search you end up with so many opinions that it makes it difficult to determine what is good and what is not. Im sure this post isn't helping any. :shog
    #3
  4. Horsehockey

    Horsehockey A GPS? Huh?

    Joined:
    Nov 17, 2010
    Oddometer:
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    What Disston said (above). How many miles on this bike? A couple points: I ride a 75 and mine was sitting for a long time too. You've mentioned that budget is an issue. With that in mind, forget about the cosmetics (i.e. seat cover) and begin the two year process of bringing this bike back to roadworthy. A new battery is a good start, and should last at least five years. Some basics: do not remove the front cover of the engine (where the alternator hides) without disconnecting the battery ground cable first. You will likely cause $$ damage to your diode board if you do. Put the bike in neutral and then on the center stand (maybe elevated with 2x4's) such that you can rotate the rear wheel in neutral. Listen for bad sounds at the transmission when you do this. Bad sounds are gravelly dry bearing sounds or "notchiness" while rotating. Sometimes bikes that sit for too long suffer bearing entropy. If crunchy sounds are heard, start saving up for a tranny rebuild (about $600 more). Before you start changing fluids, go buy a set of BMW crush washers for all the fill and drain plugs....then use new ones every time. Guys end up with stripped plug threads when they ignore this. Be patient. In a year or two you'll have a great reliable rider. Until then, all bets are off.
    #4
  5. Cordless

    Cordless Two Wheel Addict

    Joined:
    Sep 11, 2006
    Oddometer:
    2,049
    Location:
    Spokane WA
    You might also check in with the AZ Airhead club. I know there is one because we in NM have arranged some campouts together. The airheads would help you get your BMW running without replacing unncecssary parts.

    I am running a NM Airheads tech day in my shop next Saturday if you feel like making a trip. BTW, I have a Monza blue '75 R90/6 and so does another of the NM Airheads.
    #5
  6. tete

    tete clown shoes

    Joined:
    Oct 15, 2009
    Oddometer:
    346
    Location:
    Gilbert Az
    A little more info on the bike: It was parked in 2001 has 95,000 miles.

    The bike was stored indoors the entire time.

    My understanding is the bike ran flawless before the starter issue. The PO had plans to make this into a cafe bike so he opted to start the process before putting in a starter. This is all hearsay so I'll take as worth noting but I certainly wouldn't put money on it.

    The tires look very good.
    #6
  7. disston

    disston ShadeTreeExpert

    Joined:
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    Location:
    Silver Spring, Md
    The cover on the front of the engine is the "front cover". Inside this you will find the ignition points, manual advance, alternator and diode board. As mentioned by Mr. HH do not remove the front cover with out first disconnecting the battery ground strap. If the battery is hooked up and the front cover contacts the wrong part of the diode board there will be expensive sparking. Remember: Anytime the front cover is removed or replaced the battery is disconnected.

    Behind the front cover is the "timing cover". It covers the timing chain. Do not try to remove the timing cover for any reason until you have been instructed to do so by somebody who knows what is what.

    You're learning.

    You need a manual. You need at least one manual to begin with, there are three commonly available. One or two manuals may have come with the bike. Which manuals do you have?
    #7
  8. Horsehockey

    Horsehockey A GPS? Huh?

    Joined:
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    This is excellent advice. ABQ is prolly too far away for a tech session, but I would work hard to connect with the AZ membership. The R65 that you owned before is certainly similar, but has enough differences that you would benefit from learning from others. Aside from the fun, attending a tech session with a bunch of airheads can save you lots of money in the long run.
    #8
  9. tete

    tete clown shoes

    Joined:
    Oct 15, 2009
    Oddometer:
    346
    Location:
    Gilbert Az
    A little background.

    I've owned a 1981 R65 but it was pretty clean - replace the float in the carb. that was all.
    since then I have had -
    2 honda Cb200
    1 Cb125

    and 2 CB500. 1 that I still own and am selling to help fund this project. If it sales soon then I''ll have some money to put into this rather quickly.

    Here is a pic of the CB125 I just finished and sold.
    [​IMG]

    and a pic of my CB500 I am selling.
    [​IMG]

    I rebuilt the carbs in the CB500 and in the CB125s - and little things here in there. Cosmetic stuff is generally cheap and something I am comfortable doing. Also keep moral high while. On the mechanical side I am ok with following instructions but I don't have an indoor workstation so things are not as tranquil. I would say I'm novice mechanic as I have never taken the head off a bike and re-assembled it.

    Thanks for all you help. I am going to post more pics of the bike perhaps you guys can point out some of the good and bad just from the pics.

    Thanks again.
    #9
  10. Horsehockey

    Horsehockey A GPS? Huh?

    Joined:
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    It would be handy if you can find a receipt for a timing chain replacement. Some guru's recommend replacement every 50K miles or so. In any event, if your bike has 95K miles on it, a timing chain job is in your future. Don't stress out, the bike just runs a little less smooth as the chain starts eating aluminum.

    Meanwhile, I don't want to pry and ask what you paid for the bike, but if you didn't pay a ton and if you got a large tank (6 gallon with knee pads) and got an authentic BMW S fairing with it, then you may have gotten off to a very fine start.
    #10
  11. tete

    tete clown shoes

    Joined:
    Oct 15, 2009
    Oddometer:
    346
    Location:
    Gilbert Az
    I will look into joining AZairheads right away. The tach is either broken or turned for some reason. I'm sure the gauges will require a rebuild as well but that can wait.

    In the meantime here are pics of the bike via cell phone
    [​IMG]
    [​IMG]
    [​IMG][​IMG]
    [​IMG]
    #11
  12. disston

    disston ShadeTreeExpert

    Joined:
    Mar 22, 2011
    Oddometer:
    10,412
    Location:
    Silver Spring, Md
    You have the stock R90/6 carbs, 64/32/11 & 12.

    The handle bar mounted master cylinder is a very nice updated part. Makes for better brakes.

    Later model valve covers. they are quieter than the peanut style covers. At least the OP didn't chrome plate them. Like he did several other places on the bike.

    Good Luck with it. Get a manual.
    #12
  13. Bill Harris

    Bill Harris Confirmed Curmudgeon

    Joined:
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    Location:
    backwoods Alabama
    Nice find. Welcome (back) to the Asylum.

    Still, they are around a dozen years old and although the tread looks good, the tires may be dry-rotted. Although you are on a budget, don'r skimp on the tires. An orphan is an awful thing to be... :cry

    Even though it may be "due" for a timing chain, they can rattle for a LONG time and I've never heard of a timing chain failing. Put it on your "to-do" list of things to look at when time/budget catch up. And yes, if you can hook up with some AZ Airheads, a quick look and listen can tell a lot.

    You'll have plenty of time for the bike. Mine has been with me through a career, a divorce, retirement and lord knows what else and it's still a good ride.
    #13
  14. Horsehockey

    Horsehockey A GPS? Huh?

    Joined:
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    From the looks of your Hondas, you've got very good taste. The prior owner(s) of your airhead don't necessarily fall into that category. Most guys, like me for example, aren't really into the chrome effect on the original aluminum patina. What you ultimately do with the airhead is up to you, but you're off to an intriguing start. Looks like you've got an OEM S fairing. If it ain't cracked up too bad, it'll restore beautifully with a paint job. Especially handy if the mounting hardware is in the box somewhere. All very pricey if bought new. The immediate challenge is getting the basics - good electrical, good fluids, good rubber. Shelf life for tire rubber is about six years, then your safety is at risk, as Bill suggested above. Your tach is obviously fubared for the moment. Requires disassembly to put the two little screws back into the face which is a home project, but you may have to farm out the repair if the guts don't work anymore (as indicated by the spun needle). Budget? I think about $200 for shop work. As I mentioned earlier, these re-hab jobs take time and money, but once they're sorted out, they'll give you another 100K miles without substantial additional investment. At least that's the story that's worked with my wife so far.
    #14
  15. Biebs

    Biebs BMW Airhead

    Joined:
    Mar 2, 2012
    Oddometer:
    564
    Location:
    Cave Creek AZ
    Odessey PC680 battery - takes 1/2 the space as stock fits very easy. Seat cover available on Ebay $59 made to fit stock seat.


    I had the PC680 in my 74 R75/6 4years + never charge works great fits without messing with the subframe terminals match up.

    Also check mottard-eletric new wires for battery+ and _ plus the beacon 1 LED brake light kit. All money welll spent.


    http://www.motoelekt.com/lighting.htm


    :freaky
    #15
  16. chasbmw

    chasbmw Long timer

    Joined:
    Feb 19, 2006
    Oddometer:
    2,386
    Location:
    Bath Uk
    Looks good, nice bike.

    I suggest all new fluids, regrease wheel and swinging arm bearings, I strongly suggest clean and regrease of headstock bearings.

    On the starter issue, you need to find out what you have, count the teeth on the ring gear, 92 teeth = 8 tooth starter, 111 teeth = 9 tooth starter. If it is an 8 tooth a rebuild of the starter is the most cost effective solution, but new solenoids for the 8 tooth starters are difficult to find. If you have a 9 tooth starter then the cheapo Chinese Valeo copy will work fine.

    Starter problems can be due to starter relay problems and remember that 90% of airhead electrical problems are down to corrosion of the red leads at the starter relay.

    A carburetor rebuild kit is very worthwhile.

    Treat this bike as a long term project and remind your wife how much cheaper parts are than depreciation on a new one!
    #16
  17. tete

    tete clown shoes

    Joined:
    Oct 15, 2009
    Oddometer:
    346
    Location:
    Gilbert Az
    Wow. Great feedback and input. I expect to have this bike running sooner than perhaps I let on. Especially when the other Honda sells. It will have to be a long term project till it Is complete. But as far as running and reliable I expect a month or so.

    This may be ambitious but better than sleeping on it.

    First order of business is getting the battery and to see where the downfall of the starter truly is. (60$)

    As well as basic fluid changes and lubrication as well as plugs. (60$)
    New carb fuel lines and rebuilds will probably run about (60$) as well.

    So for what I figure is about 180$ I should be able to at least source the basic problems and where they exist.

    A battery tender I image is a good idea as well +$25. This to me is all within reason. Once we discover the reals problems, which I'm sure will exist, we can see how to cross those bridges.

    If anyone has a couple other things I should consider it any parts they are selling that I have mention please PM me

    The tires will be the very last thing I do as I don't expect to be riding this thing anywhere for a bit.

    I plan on doing a 600 mile road trip in Jan. on THIS bike.

    Yep.

    I know I have extra parts to sell, not everything is pictured. Extra mirrors, fenders, other bits here and there, that I will list in the classifieds to help fund this project. And I will most certainly join AzAirheads.
    #17
  18. tete

    tete clown shoes

    Joined:
    Oct 15, 2009
    Oddometer:
    346
    Location:
    Gilbert Az
    There is alot I can do on this bike at little cost. Like cleaning it!!!!!
    #18
  19. tete

    tete clown shoes

    Joined:
    Oct 15, 2009
    Oddometer:
    346
    Location:
    Gilbert Az
    So I decided to go through my box of parts that I received with the bike. If you guys could fill me in on some of this stuff that would be great. Is all of it simply bolt on mods or does this require modifications? I wasn't sure if I should post here or in the thrift mart sticky so I took the safer route. If you are looking for any of these send me a PM and once I determine what direction I am going with the bike, perhaps we can make a deal, feel free to include an offer as I need cash to get this girl rollin'. all parts look to be genuine BMW parts.

    Here is the tank, no dents a scratch as in the picture but no dents anywhere. looks good inside. matching fenders
    [​IMG]
    [​IMG]
    here is the cap
    [​IMG]
    fairing and parts that go along with it such as plenty of bracket, as well as the gauges and gauge holder.
    [​IMG]
    [​IMG]
    mirrors - I got 4 of these. all the same I believe
    [​IMG]
    seat cowl of a 100T?
    [​IMG]
    some koni shocks - look to be pretty nice!
    [​IMG]
    [​IMG]
    And bracket for saddlebag/cases - genuine BMW stamped and in new or like new condition - have both left and right sides and cowl as well.
    [​IMG]

    If the pictures are too big please send me a message to make them smaller. I will gladly downsize them (all taken with iphone.

    I also found the OEM pump. Where does that fit on the bike?

    Additionally there are all kinds of odds and ends that maybe applicable with some of the above such as brackets, wires, bolt and nuts etc..

    thanks
    again for your help.
    #19
  20. ontic

    ontic

    Joined:
    Jul 14, 2008
    Oddometer:
    1,074
    Location:
    Melbourne
    [​IMG]

    put these Konis on your bike, unless they are shot then they are better than the ones you have on there at the moment.
    If they are shot, then you can rebuild them. Koni are no more, but Ikon bought out their rights or something like that... so you can get the rebuild stuff from here
    http://www.ikonsuspension.com/
    I've got a set of Ikons on the bike and Konis on the shelf. They are pretty good.
    I got a whole bike in parts as spares when I bought my 90/6.

    I like your bike. The blue is great. Good score.
    I'll leave the rest of the parts to others.
    #20