BMW K vs. R (RS & RT)

Discussion in 'Airheads' started by Mathias, Jun 5, 2010.

  1. Mathias

    Mathias Been here awhile

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    Hi all,

    We don't see all that much talk about the early BMW K bikes around here, probably mostly because there isn't a K-GS.
    Well, I've gotten the fix-it-up bug, and am looking for something I can tour on that I can also work on. Everybody loves the R airheads, but what about those Ks? I keep hearing that they are bulletproof, but that assumes that they run well in the first place. What if it's a little tired and neglected, how much of a pain in the ass is it to rebuild, compared to an airhead? Parts costs and availability?

    Also, what about the fun factor? Do the Ks feel much more top heavy? What about the power band (I know there's more power overall)?
    And what about aerodynamics and comfort? Is the K100RS comparable to the R100RS? And the K100RT to the R100RT? Two-up?

    Thanks!
    #1
  2. blaine.hale

    blaine.hale Long timer

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    I beg to differ!
    [​IMG]
    #2
  3. coastranger

    coastranger Been here awhile

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    to be honest, this is just word of mouth and looking at price lists for parts etc
    but 2 years back my choice was between an airhead and a k bike, same year
    what I was told , on the BMWMOA site was that the k's are much more expensive when broken, the fuel injection not as user, side of the road friendly
    but everyone also pointed out they are a great ride

    so 2 years ago, I got another airhead, something I was familiar with and had the tools and experience to work on, a 85 R80RT

    my next bike will probabally be a k series or a GS
    #3
  4. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    K100RS, vibration in footpegs, hot very hot on the left side in warm weather. Well uncomfortably hot in hot weather, great torquey motor will pull out of any gear, well almost, heavy top end, better milage on highway, than R1100's and lots better than the R100's. Little harder to tune, shim and buckets for valve adjustments. Your airheads are hands down easier to work on in every aspect than the K's Parts are probably cheaper on the R100's.

    I'd say the only advantage a K has over the airheads will be power, and gas millage, and smoother tranny.
    #4
  5. durtwurm

    durtwurm Talented Amateur

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    Get a well taken care of K75. Smoooth and bullet proof. You won't be wrenching much on a good one. I have owned two. Love the R bikes and have two now but the K75 is a great ride!
    #5
  6. Zagando

    Zagando BMW uber alles!

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    A solid +1 on durtwurm's excellent advice. Early Ks, properly maintained (spline lubes, change fluids, basically) , are essentially bulletproof.

    I also love old airheads but you really can't beat a K75 or K100 for reliability.
    The trouble is, one can get bored by such a bike that doesn't require valve adjustments every 3k miles, etc. etc. Ks have also been accused of lacking personality but if that means being smooth as a sewing machine and running like a Swiss watch, well, count me in.

    I love the whine of my triple above 5000rpm---kind of my two-wheeled Porsche.:D

    Two-up touring would be a bit better on a K100 but a 75 will do fine as long as you keep the revs up when passing or going up long grades. K100s really have the low-end torque.

    Beware that RTs are going to give off more heat than you'd like (unless you're in a cold climate to begin with). The K100RS has some vibration under 70 mph that goes away at autobahn speeds. Never bothered me much but others complained about it. YMMV.

    All in all the K75S (with the sportier fairing and suspension) is one great motorcycle.

    Check out my reno thread linked below; it's been a fun project.
    #6
  7. Twinz

    Twinz Been here awhile

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    This is my friend's '85 K100 (w/R-RS fairing)...bike just turned 200,000 miles. He has many bikes but prefers this one for trips. His K has been very dependable.
    [​IMG]
    #7
  8. Harry Backer

    Harry Backer Ran when parked!

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    They are both great bikes get what ya want.
    #8
  9. bmwrench

    bmwrench Long timer

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    Hey "twinz", good to see you here. John's K100 is quite wonderful.
    #9
  10. borg

    borg Been here awhile

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    I've had two K100RS bikes (1985 and 1991) and put several 10s of thousands of happy miles on them commuting, touring, day rides in the mountains etc...

    I also have an F650 Dakar and R100GSPD in the line up. The K was a great bike until I got the 650, then its shortcomings as a inter-urban commuter bike became more apparent. It's heavy, not very nimble and has way more power than you can use in city traffic. The GSPD isn't exactly light but it eats up Seattle area roads better than the K as well. The K has pretty much sat idle for the past few years while the other two get the most use as day-to-day rides but if I needed to get from here to Spokane (or Boston) in a hurry I'd be on the K100RS. It is also (IMO) a great looking bike.

    Steve
    #10
  11. Twinz

    Twinz Been here awhile

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    Is that you, Bud?
    #11
  12. bmwrench

    bmwrench Long timer

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    Ayuh.
    #12
  13. Martian

    Martian Long timer

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    I'd like to see more of this bike.
    #13
  14. blaine.hale

    blaine.hale Long timer

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    #14
  15. Icewalker

    Icewalker Conundrum

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    :eek1 That's nice. What are the wheels off? R100GS?
    #15
  16. Martian

    Martian Long timer

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  17. SBloke

    SBloke Adventurer

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    [​IMG]

    I want one.... bullet-proof-ness of a K75 with the looks of a GS. :clap
    All it needs is a supertrapp and some nice luggage
    #17
  18. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    I haven't ridden a K75, but wonder how well the little motor, which isn't know for gobs of power would do off road.
    #18
  19. SBloke

    SBloke Adventurer

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    I think it would be a bit on the heavy side but other than that it'll just keep going. Just make sure to have a good skidplate, the front of the engine seems a bit delicate here and there.

    I might just have to give it a go and find out if I can build something like this. But first, deciding between either a K, or an R is tough enough :rofl

    K75s seems the best bang for my bucks, but less fun than an R. How you guys ever choose between them is beyond me.
    #19
  20. Max Headroom

    Max Headroom lost in the '70s

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    Easy to choose. My head tells me that a K75 would be sensible, a K75S even more so. My heart won't have a bar of it . . .
    #20