R90S vs R100S

Discussion in 'Airheads' started by DJones, Nov 1, 2010.

  1. DJones

    DJones Been here awhile

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    Ok all you historians, why is the 74 thru 76 R90s held in so much higher esteem than the 77, 78 R100S models? How do the two bikes compare in performance. A nice 90S seems to bring about twice the dollars as later models.
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  2. P B G

    P B G Long timer

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    Well teh R90S had those dellorto's, and the R100S was just bings. I think there was more HP out of the 90s, despite being fewer HP. All around more of a performance kit.
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  3. lulu

    lulu Adventurer

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    Why do people collect certain motorcycle and not others, why certain motorcycles are legendary? My guess is that the difference is mostly in people's mind, and the perception we have of a motorcycle is reinforced by what the community thinks. Collectors are somewhat conformist. The reputation of a bike will influence my opinion of a bike, even though I don't know anything about this bike...
    If you don't see any difference between an r90s and an r100s, then good for you: you can buy the r100s, it's cheaper, and you will enjoy it like an r90s. Maybe the r90s was the first one, maybe it looks a bit nicer, maybe less were built, but maybe in theory the 100s is a bit more powerful... To some people, those facts will matter more than the actual riding feelings they get from the bike. But I think you are right, objectively, nothing justifies the price of an r90s compared with an r100s.
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  4. Hawk Medicine

    Hawk Medicine Coyote's Brother

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    The R90S was a groundbreaking bike not only for BMW but for the entire motorcycling world.

    At the time it came out, it was arguably the fastest, best built, most expensive production motorcycle in the world and the first attempt by a manufacturer to build and market a cafe-racer-esque bike to the top of the market.

    Thankfully, it worked!

    The R100S kept the styling of it's predecessor but substituted an updated 1000cc engine but with Bing 40mm carbs and had a somewhat stiffer frame. The speed difference between the two is probably a toss-up but Dells are nice to have on either bike.

    The R90 is an iconic bike because it is just that, while the R100S bikes are still coming into their own and are on their way up. You should be able to snag a perfect r100S for around $5K while a perfect R90S might cost upwards of $12K.

    If you want a rider, you can usually find decent R90Ss for maybe 4K depending on location or a nicer R100S for a smidge more. Me? Given the choice I might buy the R90S and hold on to it but a sweet R100S is a nice ride!

    Come to think of it, I had that choice and went off and built my own! :lol3

    [​IMG]
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    pockomoth likes this.
  5. Max Headroom

    Max Headroom lost in the '70s

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    Values are subjective, as are opinions . . . still, here goes:

    The R90S was hailed as an instant classic when first released in late '73. The press universally loved it. The R90S enjoyed some high profile race victories thanks to Udo Geitl and Helmut Dahne, which also added to the reputation the R90S created for itself. While it was in production, it was the premium model in the BMW range, and that added further desirability.

    The R100S on the other hand merely built on the R90S's platform, and although it brought some worthwhile upgrades such as a stiffer frame, it was a development of the R90S as distinct from the R100RS which was a ground-breaking model due to the fairing. And since the R100S was no longer the premium model, it lost some of the potential appeal even though it was technically a better bike than the R90S.

    Another factor is the R90S's short production run of three years, compared to the substantially longer production run of the R100S and it's subsequent R100CS update.

    The R90S set the mold for BMW styling for the rest of the airhead production life, with the tank, gauges and seat profile creating the basic silhouette of most models to follow. The R100S didn't really create any "firsts" by comparison. It remained overshadowed by the R100RS for its entire production life, even though it was arguably the fastest production airhead available.

    I saw an article about the R100S a few years ago in a classic bike mag, and the writer unfairly (in my opinion) panned it. He did make an interesting point though when he mused that BMW perhaps may have done better if they had left the R90S in production (in updated /7 form) alongside the R100RS instead of using the 1000cc engine in both. An interesting although debatable thought . . .

    A friend of mine has had an '77 R100S for many years, and I've ridden it several times. I really liked it and felt that it was definitely a bike worthy of the "S" suffix. It has always remained a mystery to me that they have been so undervalued.
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  6. chazbird

    chazbird Long timer

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    No pictures of this, so I guess it doesn't exist on the internet, but my friend who has his own shop I've been going to for 20+ years is a real air-header and over the years has had many of them. About 4 years ago he finished a little over a year build of a R90S entirely from NOS BMW parts. The only thing that wasn't from Germany were replica new Bing carbs from Poland, although they may actually be licensed from BMW, I 'dunno. He sourced the parts from his friend who owns a BMW dealership; interesting you can still get all this stuff. He wouldn't admit to saying how much more than 15k he had in it. Its smoke gray, and obviously it came out perfect. It now has about 20,000 miles on it.
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  7. I GS 1

    I GS 1 I 90S I

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    Nothing? except that is in fact what people are prepared to pay for them
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  8. istanbulian

    istanbulian Adventurer

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    +1

    Objectively there is little to separate the 2 models; what the "market" believes is purely a subjective assessment. If you don't need the R90s's paintjob the R100S/CS offers much better value.
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  9. Rapid Dog

    Rapid Dog bikes, booze, broads...

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    ditto that one...and everything said here is true.

    One thing to remember, if you are looking to buy, is that BMW is slow to change and improve their bikes. Folklore has it that the customers bitch for years forced to design their own upgrades, then BMW finally makes the same changes and calls it their own. Call it stubborn Krautness or shrewd marketing, they are slow to move.

    That said, the R90S may be the cat's pajamas to some, but later models have improvements, high on collectable list or not.
    My favorite is a first year '77 RS (cuz I had one once uponatime). I wouldn't shop for an R90S. Personal preference.

    But seeing '77 RSs for sale now, I always stop and think...maybe I should get a later model RS...hmmmm....
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  10. Xcuvator

    Xcuvator Justa Venturer

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    I agree with everything said here and just thought I'd add that the 90S has a couple of things over on the 100.

    Better gas mileage
    Less vibration
    #10
  11. I GS 1

    I GS 1 I 90S I

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    I agree it is all subjective. The one excites people like me and the other is just another very good bike of which there are dozens. If value for money is the important factor, why are we talking BMW when there are so many good, reliable jap bikes on the market?
    #11
  12. BiG DoM

    BiG DoM African Adventurer

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    This addresses many of my own questions and sentimets - having recently bought a project '77 R100S.
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  13. Jon-Lars

    Jon-Lars Jon-Lars

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    Bing carbs? on his replica R90S?

    Wonder what else was done wrong.
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  14. carockwell

    carockwell Been here awhile

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    I think the main difference is simply that when the R90S was available, BMW could still claim that it was the ultimate sport bike, nothing else was faster. It was the number one, cost is no object, sport bike of its day. People always remember the top bike of the era.
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  15. lemieuxmc

    lemieuxmc Banned

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    Nothing else was faster?

    I think you mean "Nothing else was a better package". I'm pretty sure that the Kawasaki 750 triple, 903Z1, and CB750 Honda were faster, but didn't handle as well.
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  16. supershaft

    supershaft because I can

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    I don't think it is too objective at all to say that if you put Dellorto carbs on a R100S you have got a bike that is at least a little bit better than a R90s in so many aspects. A lot of the R90S's performance gains came from those carbs. The same thing can be had again and on top the stock R100S IF they had the same carbs as a R90S. Put dell's on the R100S and the contest is over IMO. Especially if you are comparing '74's to '77's. I think the R90S has a bit higher CR than the R100S? I know the R90S has a lot smaller ports. If the compression is higher, that comparatively probably helps lower rpm power more along with the smaller ports. I suspect many riders that never rev their engines much mike like the smaller ports/higher CR combo? But then again, nothing helps power across the board like more cubic centimeters.
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  17. BiG DoM

    BiG DoM African Adventurer

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    Is the R100S also not the large valve engine? I think the Bings on the R100S are 40mm and while maybe were not as responsive as Delortos they sucked more air?
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  18. supershaft

    supershaft because I can

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    Big port heads have bigger intake valves as well. 44mm versus 42mm. They also have much larger ports. Most people call them big valve heads versus small valve heads. I call them big port heads versus small port heads. Why? Because it is very easy to put 44mm valves in in small valve heads AND they work very well. IMO, the main difference in the heads is not the size of the intake valves but rather the size of the ports!

    Sure the 40mm bings flow more air than the 32mm Bings but the Dellorto's are much better performing carbs in almost every performance aspect. I think it is safe to say that the 40mm Bings just get you more of what the 32mm Bings are. Many, many tuners do not like where that takes them.
    #18
  19. wirewrkr

    wirewrkr the thread-killer

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    ???????
    Bings?
    Why is it "obviously" perfect?
    Pictures, or the :topes factor is gonna get deeper and deeper around here
    #19
  20. supershaft

    supershaft because I can

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    And I really liked the way his post started off. That had me laughing.
    #20