1975 R90 new to forum

Discussion in 'Airheads' started by hoodun, Jun 22, 2012.

  1. hoodun

    hoodun Been here awhile

    Joined:
    Jun 21, 2012
    Oddometer:
    151
    Location:
    San Francisco, CA
    new 1975 Airhead here. Though it was the ugliest bike I have ever seen when I first saw it and now I cant stop looking at it. Shes in bad shape though the engine spins. Paid a grand for her, maybe too much?

    So far I have cleaned the carbs and ordered a dual caliper front end. Paid 450 for the entire front with the calipers. Again, maybe too much but from what I have read, I definitely want dual discs as a city rider. Possibly also an upgrade to a handlebar MC. I started to strip the paint on the tank which was in bad shape. May go with a classic black w white stripes or a non metallic grey. Not sure yet. Tank is also getting another coat of Red Kote which was seeping into the carbs from the bike sitting with gas. Plates read 1993... Odometer reads 11k (cant be right by the looks of the rubber on the pegs)

    1.) bike is covered in oil, may need to do a complete gasket/ seal replace
    2.) need to find a right side rotor
    3.) may also upgrade the MC to a handlebar type or will need to rebuild the current one
    4.) need a battery/ some sort of custom battery case cover/ I dont plan on having the side covers (prefer the look without)
    5.) slightly lower bars that are not severely pitted
    6.) need a new headlight glass piece
    7.) at least a new rear tire, front is still ok
    8.) new seat cover or seat (cafe?)
    9.) do something about the peeling chrome on the valve covers

    Here is the beaut:
    [​IMG]
    [​IMG]
    [​IMG]
    #1
  2. disston

    disston ShadeTreeExpert

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    Looks like the USA bars. Several options for stock lower bars. S, CS, RS, maybe more. The stock bars are Magura.

    Get it running before fixing brakes, Daaaah.

    Welcome.
    #2
  3. hoodun

    hoodun Been here awhile

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    My first priority is to get it running. Just waiting on some final carb parts (float valves). Once I get it running though Im gonna want to ride it. Hence why Im getting the paint started the brake parts, etc. Ill get her running, whatever it takes.

    Also, Im missing the tubing that connects the carb to the head. When I bought the bike the carbs were in a bag. cant find a source for this.
    #3
  4. villageidiot

    villageidiot Long timer

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    its just a little piece of hose. get familiar with maxbmw.com and there micro fiche online catalog.

    youd be amazed what the local bmw dealer can get
    #4
  5. daveoneshot

    daveoneshot Been here awhile

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    Dec 14, 2010
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    Google up " Hucky's BMW Parts ".
    #5
  6. Hawk Medicine

    Hawk Medicine Coyote's Brother

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    NOR CAL
    Buy a shop manual.
    #6
  7. hoodun

    hoodun Been here awhile

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    I know your all going to say I should powder coat the frame.... I gave it much though and form the looks of the original frame paint, I would like the option to touch it up easily in my garage with some shelf chasis paint, or epoxy.

    Did a test run with epoxy VHT paint. It says it weather resistant? Came out very good aesthetically. The top bar is a little rough because I didnt sand it all the way down. I really just wanted to give it some temporary coverage since it was bare metal. In a week I may shoot the whole frame with this epoxy as a sealer and then possibly go over it with a uv resistant chasis paint, or maybe even just leave it.

    Amazing you can get epoxy paint in a spray can. The auto paint place in town can make an epoxy can for 25 but it is only good for a week. it then starts to dry up. Not sure how VHT makes it last longer than a week. Maybe its not real epoxy paint, but rather a marketing gimmick. Time will tell.

    I have no reason to pull the engine so I' will paint around it. save me having to wrestle with it. Unless my friend succeeds in convincing me to pull it out.


    [​IMG]
    #7
  8. hoodun

    hoodun Been here awhile

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    On to the carbs. I throughly cleaned these and reassembled except for the floats which I am waiting on pins for. The floats are ugly but I tested them and they do float with 1/3 of it out of the water. 50 for a new set is a bit pricey to me.

    Also the bowls are a little pitted. They are still not leaking after testing. To keep parts cost from skyrocketing Im holding out on buying new bowls. One day before a long trip I will splurge the 150 towards new bowls and floats.

    [​IMG]
    #8
  9. villageidiot

    villageidiot Long timer

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    boil them float bowls in some pine sol. Also, ask around (fleamarket on here, ibmwr.org marketplace) for a set of bowls if they're too bad. Can also whip up a soda blaster on the cheap, and blast the corrosion out of the inside

    As to the frame. If you've got it torn that far down, pull the motor and do it once right. Otherwise, it'll constantly be nagging ya that you coulda woulda shoulda (at least it would me)
    #9
  10. blaine.hale

    blaine.hale Long timer

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    It's really not that difficult to pull then engine when you've reached the point you're at now.
    Don't half ass 2 jobs, whole ass 1 job.

    Good luck!
    #10
  11. disston

    disston ShadeTreeExpert

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    Those bowls look fine. The only thing that goes wrong with carb bowls is they get holes in them from corrosion. No holes, no problem.

    Floating floats in gasoline is pretty useless. Those are ready to be changed and you can expect to change them now every two years. Some do it every year. The way to test them is by weighing them.

    A major source of problems with these carbs is the enrichner circuits. Don't mix them up from side to side or mix the parts orientation with in the carbs. New enrichner gaskets and Blue Locktight on the screws.

    You have a friend? I forget when was the last time I had one of those. He can help you lift the engine out. That's what friends are for.
    #11
  12. Boxer Metal

    Boxer Metal Mad Scientist

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    Location:
    Chico, California
    Welcome and congrats. There are a lot of us Airhead folks in Northern California. You picked a great forum to get advice and help. Keep the progress pictures coming.
    #12
  13. hoodun

    hoodun Been here awhile

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    Carbs are coming along. New floats and gaskets. Oiled the butterfly shaft with a touch of oil. That one float bowl on the left bothers me and will eventually be replaced. Its very close to being corroded all the way through in certain areas.
    [​IMG]


    Gasket and seal kit came in from BMW Hucky. I already put the oil pan gasket on:
    [​IMG]


    The engine is now out as suggested (I am whole-assing it) and I will be sanding the frame down epoxy priming it and then painting it with my hvlp gun. I'm leaning towards the paint matching the tank like they used to do with these bikes before heavy production came into the picture and then all the frames were black.
    #13
  14. hoodun

    hoodun Been here awhile

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    Replacing the Main Seal. I, of course, after much reading, blocked the crankshaft and put the pistons at Top position. All seems to be going well though Im not sure its in all the way. The old seal seemed to be in much further. Maybe it was my makeshift tool that didnt work? I cut out a piece of wood in a circular shaped and used the bolts to press the seal in. Seemed to work ok.
    photos tell the story:
    [​IMG]
    [​IMG]

    The clutch plate is kinda a mess. It seems as thought the transmission seal may be leaking as there is more oil on that side, as opposed to the main seal area which wasnt that bad. The oil pump cover is a different story. . Maybe it was the oil pump cover that caused all this. What a fuckin mess. My hands are covered in oil sludge from cleaning all this. The oil pump gasket was replaced along with some copper high temp gasket material along the edges of the cover, since the gasket just doesnt seem like enough on its own:
    [​IMG]
    #14
  15. dr650dave

    dr650dave Adventurer

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    Mar 26, 2006
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    Good job on the thread Hoodun. Nice pics and info. I like seeing these neglected bikes brought back. I have an R80 I'm going to start in a couple months.
    #15
  16. ghostdncr

    ghostdncr Burnin' daylight...

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    Man, I love these "LOOK WHAT I FOUND!!!" airhead threads. :D
    #16
  17. hoodun

    hoodun Been here awhile

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    I received the new rings. I wanted to replace the old style oil ring with a more modern design. San Franciscans can get smug if you blow oil onto the sidewalk and into their faces... I read that upgrading the oil ring will help with smoke. I get how the new oil rings go on though Im not sure how in the hell the other two go on. The middle one is in two pieces, or is that the top one? I cant find any info on this style ring. Also the g ring is completely square. There is no taper to it at all, which I believe the top ring should have? Confusing as hell. Anyone ever come across ring like these?[​IMG]


    Here are the old style rings:

    [​IMG]
    #17
  18. hoodun

    hoodun Been here awhile

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    Finally finished with the paint. Could not resist the classic black color scheme. I also base and cleared the frame to give it more of the single color scheme look of the older airheads.

    The reassembly can now start.

    [​IMG]

    [​IMG]
    #18
  19. Kt-88

    Kt-88 I like everything.

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    Beautiful paint. Did you lay the stripes by hand?
    #19
  20. tete

    tete clown shoes

    Joined:
    Oct 15, 2009
    Oddometer:
    346
    Location:
    Gilbert Az
    geez man great stuff going on here! tank looks soo fresh soo clean.

    I kinda can relate in some regards but your bike was in far worse shape than mine. Got mine for $1300, but mine came with an S fairing, xtra tank, luggage racks, fenders, gauges, etc.. I kinda got a bit lucky for sure.

    Your bike is going to be sweet when finished. :clap

    if you need a /6 seat hit me up I have an OEM one with a new moto bins cover I was about to put up for sale.
    #20