Fetching my next airhead

Discussion in 'Airheads' started by AlpineRAM, Jan 25, 2011.

  1. LasseNC

    LasseNC XSessive!

    Joined:
    Jan 27, 2008
    Oddometer:
    1,077
    Location:
    Denmark, Danimarka, Danmark, Dänemark
    It is a weird bike, seems to have gotten alot of love with all the modifications, and then at some point it turned.
    #21
  2. jellycow

    jellycow Back on track!

    Joined:
    May 29, 2005
    Oddometer:
    1,018
    Location:
    South side of the Netherlands
    I've always loved the K fairing on a airhead. How did they mount it, does it look like a bolt-on or did they have to change a lot? Could you post some pics of the mounting maybe, to get the idea?
    #22
  3. squish

    squish Out of the office.

    Joined:
    Dec 4, 2003
    Oddometer:
    6,458
    Location:
    Where the Ghetto meets the sea.
    Is this the bike that used to be an ungodly mix of colors
    Like Yellow, gray and purple,

    Seems like there was a buy thread where the PO bought the bike and then de uglied it and painted it red, including the tesstarossa
    #23
  4. AlpineRAM

    AlpineRAM PartsChaser

    Joined:
    Nov 16, 2007
    Oddometer:
    199
    Location:
    Europe, Austria
    Well, something for the history buffs:

    This bike was built by Hinterreiter, a company that was competing with HPN in the 80s, modifying the 80GS.
    They shared the same basic forks (Marzocchi M1), but they had completely different approaches to frame and drivetrain issues that come up if you lift a bike. (Think much more leverage to the steering head)
    Hinterreiter did the K fairing stuff, the mount is the stock K fairing mount secured to the steering head on the frame with a single U-Bolt. The rear mounts are some tabs welded to the frame.
    Since these bikes were not engineered well almost all the frames cracked, and the bikes got scrapped. I found that what I took for cracks in the frame were the result of an extremely sloppy paint job, after cleaning and magnetic flux analysis: No cracks!
    The rear swingarm is an example of the "engineering" committed. To get the angle right they simply cut out approximately 1/3rd of the lower side of the pipe where the driveshaft is, and welded another segment of pipe to it. This gives you roughly a figure 8 with the center horizontal bar removed. Then they welded approx. 4" of pipe to the end of the swingarm, and attached the final drive. Now with the swingarm steeper and longer- voila, long suspension travel. The problem that the stock shock could not cope was solved by adding a second shock, and attaching a stub to the left side of the swingarm.
    No need to put on a double swingarm like HPN did, a lot of iron welded to various bits and pieces of the swingarm should keep it stiff enough...

    With the input shaft up there and the stock final drive the oil level and therefore the lubrication of the final drive is not great. The oil level bolt is now turned way down, and if somebody used it to check oil level the final drive almost emptied out.
    The instrument cluster is a stock R80GS cluster, but the front and lower part were ground away, and the cluster was glued to the fairing. Nobody should ever need to change a bulb in there..
    Many more pieces of moronic engineering are to be found on this bike- but except for the fork and the upgraded front brake they are all original vintage 1980s lunacies. :D
    I am pondering restoring the bike to it's original state, including the small front brake, and keeping it for it's rarity. (I might have a lead on some HPN GS, that would be the ridable and safe version on the same theme)

    Until the 90s only 33 of these bikes were built... restore it to it's former lunacy, use it as a parts bike, get an HPN frame, swingarm, forks etc...
    So many questions..

    AlpineRAM
    #24
  5. Airhead Wrangler

    Airhead Wrangler Adios Mexico

    Joined:
    Mar 4, 2008
    Oddometer:
    6,630
    Location:
    Back in Seattle, FINALLY
    I'd say those are the RIGHT forks for that bike. The wrong ones are the ones that came on it stock.
    #25
  6. fishkens

    fishkens Long timer

    Joined:
    Nov 14, 2009
    Oddometer:
    5,222
    Location:
    Seattle, WA
    Thanks for the history. I love hearing about different "solutions" to common problems.
    #26
  7. AlpineRAM

    AlpineRAM PartsChaser

    Joined:
    Nov 16, 2007
    Oddometer:
    199
    Location:
    Europe, Austria
    Well, pondering did not get me any further, so I pulled most of the bike apart, changed the fluids etc and got it on the road. (After fixing some really stupid stuff like the throttle grip rubber being greased so that even if you held the throttle open the inside would rotate back to idle, diagonal turn signals :huh , foot amputating rear luggage holders, etc)

    Sometime in it's history somebody must have had a discussion with some engine parts. Even with a dirty air filter it only takes 1/3 throttle to get 5th gear over 7k rpm on flat ground. On a 9% slope you need full throttle to get 5th above 7k rpm, the speedo says 150 km/hr at that rpm.
    It rides really nice and is quite agile, but now the final drive bearings have developed some play. Maybe I'll use the opportunity to give her some longer legs by going to 32/10 or 33/11 from the 37/11 that seems to be installed right now.

    I am quite curious about what is going to become of this bike.

    Sorry, no pics at the moment, I was too busy turning wrenches and riding.

    AlpineRAM
    #27
  8. StephenB

    StephenB G(/)S ... what else!

    Joined:
    Aug 24, 2005
    Oddometer:
    2,044
    Location:
    Ontario
    Is that a K-tank on it? And what going on there at the top half of the front engine cover behind the oilcooler? Or is this just the low resolution image?
    #28
  9. AlpineRAM

    AlpineRAM PartsChaser

    Joined:
    Nov 16, 2007
    Oddometer:
    199
    Location:
    Europe, Austria
    There is nothing going on behind the oil cooler, except for some dirt..
    The tank is a stock Dakar tank, but it has been modified for people with long legs by elongating the stock knee "dents".
    #29
  10. AlpineRAM

    AlpineRAM PartsChaser

    Joined:
    Nov 16, 2007
    Oddometer:
    199
    Location:
    Europe, Austria
    Well, the final drive insisted on making a lot of noise, and converting fresh oil into something that looked like cow manure with metal glitter within less than 200 miles.
    So I tore into it and found that sometime in the past somebody had disassembled the drive and left out the cover gasket to mask that the big bearing had developed some play. (an interesting idea to get a lot of axial preload on a ball bearing that is already loud)
    Now I am looking for a ring and pinion set in either 32:10 or maybe even 33:11(if available in 3 bolt) and all the bearings, gaskets, shims etc.

    On a lighter note the amount of water that can be present in a shaft housing without corroding everything to hell is amazing.

    AlpineRAM

    (now you understand the "parts chaser" under my avatar :lol3 )
    #30
  11. AlpineRAM

    AlpineRAM PartsChaser

    Joined:
    Nov 16, 2007
    Oddometer:
    199
    Location:
    Europe, Austria
    Well, final drive restored, (stock ratio), brakes overhauled, gearbox overhauled, engine etc... Except for a now leaking fuel tank it's OK...
    And it's fun to ride!

    [​IMG]
    #31
  12. JPSpen

    JPSpen At Large

    Joined:
    Sep 3, 2007
    Oddometer:
    1,186
    Location:
    Keeping up with the Joneses, OK ?
    Good job getting her back on the road..

    She looks pretty damn unique to me...

    And most BMW's don't...

    Congrats on the cool ride..

    John
    #32
  13. AlpineRAM

    AlpineRAM PartsChaser

    Joined:
    Nov 16, 2007
    Oddometer:
    199
    Location:
    Europe, Austria
    As it is said - all things worth doing, are also worth overdoing....
    I got yet another airhead for me.
    My wife did not complain because I bought her an airhead too- R100RT for her.

    Let me proudly present HPN #411
    [​IMG]I still need to sort out some paperwork to get her plated, but as far as I can tell this is even gonna be more fun than the Hinterreiter I still have..

    Cheers!
    AlpineRAM
    #33
  14. Kt-88

    Kt-88 I like everything.

    Joined:
    Sep 9, 2012
    Oddometer:
    890
    Location:
    SLC area, Utah
    Neat!
    #34
  15. mendoje

    mendoje Been here awhile

    Joined:
    Jun 6, 2009
    Oddometer:
    251
    Location:
    Los Angeles
    Can you post pics of the swingarm and rear suspension, showing the modifications and features you mentioned above?

    Great job on bringing this bike back to life!
    #35
  16. blaine.hale

    blaine.hale Long timer

    Joined:
    Feb 28, 2009
    Oddometer:
    3,281
    Location:
    Atlanta, Ga
    But it has street tires :(
    #36
  17. AlpineRAM

    AlpineRAM PartsChaser

    Joined:
    Nov 16, 2007
    Oddometer:
    199
    Location:
    Europe, Austria
    I ordered a set of Michelin Anakees (I have the Anakee2 on some bikes and really like it)
    [​IMG]

    I got Anakee 3 ... looks like a street slick with some proforma grooves.
    [​IMG]
    I am really curious how this will work. If I don't like it I hope that they still have the Sirac.

    [​IMG]
    #37
  18. Kokopelli

    Kokopelli Yeah, right!

    Joined:
    May 2, 2003
    Oddometer:
    4,737
    Location:
    Rapaura
    Those are street tires as well.
    #38
  19. R-dubb

    R-dubb Dubbious Adventurer

    Joined:
    Aug 4, 2001
    Oddometer:
    5,099
    Location:
    San Francisco
    Nice :clap:clap

    Now that's a step in the right direction.
    #39
  20. Tanami

    Tanami Under The Weather

    Joined:
    Mar 26, 2006
    Oddometer:
    315
    Location:
    Far, Far Away.
    A hint of the Hinter! A mythical beast indeed. I have seen images of these bikes over the years (one pic with two in motion and side by side is in my mind??) but knew nothing of the story. It is great to read and see more. Your new HPN is mighty fine...not doubt ...they all are... but the hinter is uniquely historical, if not brilliantly engineered. A great find. Keep us posted on what you find about it. I'm just pleased you shared it. Stu
    #40