Results 1 to 13 of 13

Thread: Difference between 81-84 R100RS and an 89 model year

  1. #1
    Registered User
    Join Date
    May 2014
    Location
    Reading, PA
    Posts
    50

    Difference between 81-84 R100RS and an 89 model year

    I am new to this to an extent. I think they changed to a mono lever rear suspension and the side cover is different. Any other notable differences between an early 80's and late 80's R100? There is a 1981 R100RS that has caught my eye

    http://www.ebay.com/itm/81-BMW-R100R...vip=true&rt=nc

    as well as a 1989 R100RT

    http://www.cycletrader.com/listing/1...0-RT-112833442

    Any education is welcome. I understand the difference between an RS and an RT. Well, maybe not completely.

  2. #2
    Administrator 20774's Avatar
    Join Date
    Sep 2005
    Location
    San Antonio, TX
    Posts
    13,364
    Well, at least the '89 has the valve covers on right!

    I think you have the major differences...there are probably some other styling changes. One thing will be that the pre '85 model will have the circlip installed inside the transmission, generally thought of as a good thing. Around '85 until just before the final year of production, the circlip was eliminated, and thought to result in internal gear issues. The issues don't show up immediately but tend to over time.

    For specifications, compare the numbers from these pages:

    - '81-84 RT bikes: http://www.bmbikes.co.uk/specpages/R100RT.htm

    - '89 RT bikes: http://www.bmbikes.co.uk/specpages/R100RTmono.htm
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  3. #3
    Registered User
    Join Date
    May 2014
    Location
    Reading, PA
    Posts
    50
    Thank you.

  4. #4
    Registered User lkchris's Avatar
    Join Date
    Mar 2003
    Location
    Albuquerque, NM
    Posts
    4,856
    VERY major differences

    The main frames are different, as is the rear subframe. Saddlebag mounts are not interchangeable. Neither are seats. Much improved centerstand on newer bike.

    Newer bike has K-bike forks and front brakes. Newer bike has drum rear brake instead of disc. This is better.

    Newer bike has 32mm carbs as opposed to 40mm and smaller valves to match. This is also good, as the earlier valves were so big as to weaken the heads. Newer bike has 8.5 as opposed to 8.2 compression. Different exhaust systems. Exhaust valve recession problem solved on newer bike.

    Newer bike has almost nothing of the electrical system inside the headlight. It will have single as opposed to dual coils.

    Newer bike has wheels approved for tubeless tires, which older bike does not. Front wheel on newer bike is smaller diameter.

    Newer bike is approved for use with top box, which older bike isn't.

    Newer engine is likely to have folded over edge to filter canister, meaning you don't use the metal protective washer.

    Newer bike will not have oil cooler which older bike will.
    Last edited by lkchris; 08-18-2014 at 02:33 AM.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  5. #5
    ABC,AMA(LIFE),MOA,RA,IBMW MANICMECHANIC's Avatar
    Join Date
    May 2003
    Location
    Manitowoc, Wisconsin
    Posts
    2,080
    Also the newer bike will have more anti-smog plumbing under the starter cover.
    F.O.G.Rider, Rounder #6,
    Ambassador, Biergarten co-chair
    BMWRA Wisconsin Region Rep, camping chair

  6. #6
    Registered User toooldtocare's Avatar
    Join Date
    Mar 2008
    Location
    Lake Saint Louis, MO
    Posts
    1,741
    And I'm not sure of this bike (the RT), but it may have the oil cooler. My 95RT had one, and so did my 88 R100RS. Everything else Kent said is right. That said, I love RS bikes, and if I were looking, I would chose it simply because it is an RS.

  7. #7
    Registered User
    Join Date
    May 2014
    Location
    Reading, PA
    Posts
    50
    What is a reasonable price for the 81 RS?

    Thanks to all for the input.

  8. #8
    Administrator 20774's Avatar
    Join Date
    Sep 2005
    Location
    San Antonio, TX
    Posts
    13,364
    Another difference not mentioned is that the pre '85 models will have the poor metallurgy for seats which exhibited rapid valve clearance closure over time...the fix is to update the metallurgy (seats and valves) with the post '85 parts.

    A point of reference for cost might be from this:

    http://www.nadaguides.com/Motorcycles

    Prices might be a little low...$2805 for a very good R100RS...might be more like $3.5-4K??
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  9. #9
    Registered User lkchris's Avatar
    Join Date
    Mar 2003
    Location
    Albuquerque, NM
    Posts
    4,856
    Quote Originally Posted by MANICMECHANIC View Post
    Also the newer bike will have more anti-smog plumbing under the starter cover.
    More plumbing for sure ... for fuel vapor recovery.

    I might have mentioned in my note above that due to the electrical system change the newer bike has less fuel capacity.

    And maybe they did continue with oil coolers. With the change to smaller valves and 30-degree valve seats they really didn't need to.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  10. #10
    Registered User toooldtocare's Avatar
    Join Date
    Mar 2008
    Location
    Lake Saint Louis, MO
    Posts
    1,741
    Quote Originally Posted by dennisarner View Post
    What is a reasonable price for the 81 RS?

    Thanks to all for the input.
    The prices are all over the place. But, I have seen nice ones for as low as $4,500 and as high at $7,500, even more. How it looks, the miles and how it rides is more important than the year when you are talking about the double shock bikes. I guess you can say that about anything though. There were a few special models out there too, such as the 78 Motorsport. Nice ones of those can go for more (mine sold a few years ago for $13K), but they are not worth it unless you are a collector, it is mostly just paint.

  11. #11
    Registered User
    Join Date
    May 2014
    Location
    Reading, PA
    Posts
    50
    I found one locally I am going to see on Thursday. 81 R100rs all original 33k miles. If it suits I will buy it (taking a trailer with me). I will update. My other rs is sold.
    Last edited by dennisarner; 08-20-2014 at 07:10 AM.

  12. #12
    Registered User lkchris's Avatar
    Join Date
    Mar 2003
    Location
    Albuquerque, NM
    Posts
    4,856
    '81 isn't the best year.

    They improved the centerstands and the transmission in if not '82, then '83.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  13. #13
    Registered User georgej's Avatar
    Join Date
    Aug 2007
    Posts
    324
    I saw a 1979 RS on ADVrider last year sell for around $8000,I think the price was.I tried to sell my '78 RS a couple of months ago with no luck.I'm not trying to make a lot of money on the bike but I want most of my money back.I completely restored the bike,it really needs nothing.Ebay brought bids a little over $4000,that was it.I also had people telling me the bike is not an true Motorsport Edition.That is a whole other thread in itself.
    Anyway,the prices are all over the place. Like any other Airhead though,the cheap ones usually end up being pretty expensive after sorting them out.I really like mine,the more i ride it the more I like it.I'm only trying to sell the bike to get a one owner 1977 R100S.
    1978 R100RS
    1978 R80/7
    1977 Triumph Bonneville
    1980 Honda XL500S

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •