old R90/6

Discussion in 'Airheads' started by US_Marshall, Aug 3, 2012.

  1. US_Marshall

    US_Marshall Adventurer

    Joined:
    Jul 25, 2012
    Oddometer:
    47
    Location:
    Ct
    I did not fine an introduction thread so ..... here I am.:D

    I acquired an old R90/6, a little research shows it is a 75. It was sitting under a cover for about 5 years at a boat yard next to salt water. I am now working on patching it back together, the prior owner/rider did not take care of it. The head light was a 7" seal beam bulb ducktaped to the housing, old rust gas and rust residue in the carb bowls (fuel was off) showing he had been running bad gas through the engine. I cleaned the tank and installed a battery and fired right up. Runs pretty well for a bike that has been stashed in less then favorable conditions.

    The odometer reads 2,200 miles, I wonder if has been rolled over already?


    Things done:

    changed oil
    fixed wiring (still needs flasher relay)
    cleaned carbs
    cleaned tank
    new fuel lines (with filters)
    Make new head light (stock reflector, different glass)
    remove luggage rack+back rest
    adjusted valve lash
    modified center stand to place battery under transmission


    Things to do:
    replace front brakes
    new rear main
    relay
    new tires
    Change ALL fluids

    Then it is ready to hit the road.

    [​IMG]

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    #1
  2. R100LT

    R100LT Chasing 11

    Joined:
    Jan 16, 2012
    Oddometer:
    633
    Location:
    Donnybrook Western Australia
    Apart from the seat ... not too shabby... well done

    Enjoy
    #2
  3. disston

    disston ShadeTreeExpert

    Joined:
    Mar 22, 2011
    Oddometer:
    12,366
    Location:
    Silver Spring, Md
    Welcome. You are right, no intro other than right here.

    Seems an innovative headlight set up. No idea what's wrong with stock battery position. Parts are available if the old battery box is rusted away.

    Paint looks in great shape for a 102K bike. Can't imagine it has not been around at least once.
    #3
  4. Rob Farmer

    Rob Farmer Long timer

    Joined:
    Aug 27, 2002
    Oddometer:
    6,750
    Location:
    Loughborough, Leicestershire. England
    The PO wants shooting for painting the mainstand that colour :D Apart from that it looks ok and wouldn't cost too much to sort out. the 90/6 is a lovely bike once it's setup.
    #4
  5. Wirespokes

    Wirespokes Beemerholics Anonymous

    Joined:
    Jul 26, 2002
    Oddometer:
    8,724
    Location:
    Jackson's Bottom Oregon
    Not a bad looking bike at all. And who knows how many miles are on it? The odometers frequently fail and this could be a replacement unit, so it's anybody's guess as to mileage.

    I've never seen a headlight like that! What is it? Definitely more aerodynamic than the stock Bosch!
    #5
  6. Beater

    Beater The Bavarian Butcher

    Joined:
    Sep 3, 2009
    Oddometer:
    3,701
    Location:
    Atlanta, GA, USA
    I have a battery try that will fit that .... PM me if interested. Fred
    #6
  7. crazydrummerdude

    crazydrummerdude Wacky Bongo Boy

    Joined:
    Nov 28, 2006
    Oddometer:
    7,926
    Location:
    El Segundo, CA
    Are those fuel lines super kinked in that setup?

    Also, I can't tell exactly, but it looks like you've got the wrong battery in there. I had a little cheapo one in my R90/6 for a while and I had it up on a wood block in the tray. :lol3

    Throw some fork gaiters on it, get some new oil and tires, switch out the fuel lines, and you're good to go.
    #7
  8. disston

    disston ShadeTreeExpert

    Joined:
    Mar 22, 2011
    Oddometer:
    12,366
    Location:
    Silver Spring, Md
    Notice the cut out in the air filter cover? The air filter sits above the trans and on the lower engine side there is a little hole on both sides. See it? Using a tee arrangement in the fuel lines a cross member, fuel line, goes through here. Not a biggy but somehow it looks funny with out it. When fuel gets low the two cylinders will run on their respective sides of the tank with out it. So it has a sort of purpose.

    Those are later model petcocks. But that's OK.
    #8
  9. US_Marshall

    US_Marshall Adventurer

    Joined:
    Jul 25, 2012
    Oddometer:
    47
    Location:
    Ct

    I have the original T fittings and will be installed with new lines and filters after the fuel system is finished, the fuel in the tank still looks orange if i shake it up (off the bike) so it still needs more flushing.

    I painted the center stand, after cutting and welding I didn't have any black paint so this was the best I had at the time.

    I have the stock battery tray, it is in good condition too, the battery is going to be relocated under the transmission. The current battery is only a 35CCA but turns over and starts right up so it will stay till I am sick of it.
    #9
  10. US_Marshall

    US_Marshall Adventurer

    Joined:
    Jul 25, 2012
    Oddometer:
    47
    Location:
    Ct
    The mufflers are rotting from the inside, there are holes and some odd rust cracks in it. So I decided to change the system.
    I started with a header off a R1150, cut the inlet off where it is ovaled

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    . I added on 4 inches of strait pipe to match the old heads. The header had to be widened about 1.5" to line up. Heated it cherry red near the merge point and wedged the header apart. Welded up a new extension and fitted an aftermarket muffler.

    [​IMG]

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    Since the carbs need to be rebuilt, I'm going to rejet it too.


    I overhaled the front brakes, new EBC pads, braided hose, cleaned master cylinder and replaced the outer seal. The rotor was grooved on the inside so I resurfaced it. It is .010 under specs now though.

    I would like to replace the disc on the hub but can't find what I am looking for. Does any one have the diameter of the mounting for the 5 bolt rotor? without cutting the rivits off and mic'ing the the rotor hat I get 5.655.
    #10
  11. Schlivitz

    Schlivitz Mercury Freefall

    Joined:
    Sep 12, 2010
    Oddometer:
    74
    Location:
    East 10EC
    I'm diggin that bulbous headlight. Does it have any ID on it?
    #11
  12. Boxer Metal

    Boxer Metal Mad Scientist

    Joined:
    Nov 3, 2003
    Oddometer:
    3,609
    Location:
    Chico, California
    x2 on that groovy headlight.
    #12
  13. US_Marshall

    US_Marshall Adventurer

    Joined:
    Jul 25, 2012
    Oddometer:
    47
    Location:
    Ct
    t is a Writeway lens, came off a mid 30's Chrysler (I think). only took a little grinding of the glass to fit into the BMW reflector.
    #13
  14. Schlivitz

    Schlivitz Mercury Freefall

    Joined:
    Sep 12, 2010
    Oddometer:
    74
    Location:
    East 10EC
    So, I won't be pickin' that one up at PepBoys.
    That's probably a good thing. It would be hard to justify from a "form follows function" stance. But if anyone can think of a functional advantage.......
    #14
  15. US_Marshall

    US_Marshall Adventurer

    Joined:
    Jul 25, 2012
    Oddometer:
    47
    Location:
    Ct
    Just a crappy cell pic, but it shows the direction I am going.

    [​IMG]

    The tank fits OK, I plan on modifying the front are to clear the master cylinder, the back looks like it need little work to fit securely.
    #15
  16. disston

    disston ShadeTreeExpert

    Joined:
    Mar 22, 2011
    Oddometer:
    12,366
    Location:
    Silver Spring, Md
    I like your Airhead, congratulations. Great job on the headers. I'll try to keep that in mind.

    And yes, the Lens!!! We've got to find some more.
    #16
  17. Rightshiftrick

    Rightshiftrick Been here awhile

    Joined:
    May 27, 2005
    Oddometer:
    120
    Location:
    New Hampshire- USA
    Are you getting rid of the stock tank? If so, I'm interested. I've got a '74 R90/6 that I brought back from a similar condition. The 90/6 series makes for a great machine.

    Erich
    #17
  18. US_Marshall

    US_Marshall Adventurer

    Joined:
    Jul 25, 2012
    Oddometer:
    47
    Location:
    Ct
    Not any time soon, I need to keep it so if the K bike tank fails I still have the stock one to go back to.
    #18
  19. US_Marshall

    US_Marshall Adventurer

    Joined:
    Jul 25, 2012
    Oddometer:
    47
    Location:
    Ct
    Installed my new top brace and clip on's. started trimming the tank to fit down over the frame, still needs to be modified to get lock to clock steering. Rebuilt the carbs and installed some velocity stacks. probably run the stock tank though.

    [​IMG]
    #19
  20. Kai Ju

    Kai Ju Long timer

    Joined:
    Jul 29, 2009
    Oddometer:
    2,196
    Location:
    Long Beach, California
    I've thought about a K bike tank before but had not considered using the front fender on the rear.

    I'll be watching this one, so hurry up would you ?
    #20