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Difference between 81-84 R100RS and an 89 model year

dennisarner

New member
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-R100RS-Mint-/161338843904?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2047675.l2557&nma=true&si=7jlowLGGMrBPXI%252F8kR0zRjl8rhY%253D&orig_cvip=true&rt=nc

as well as a 1989 R100RT

http://www.cycletrader.com/listing/1989-BMW-R-100-RT-112833442

Any education is welcome. I understand the difference between an RS and an RT. Well, maybe not completely.
 
Well, at least the '89 has the valve covers on right! :thumb

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
 
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.
 
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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.
 
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??
 
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.
 
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.
 
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.
 
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'81 isn't the best year.

They improved the centerstands and the transmission in if not '82, then '83.
 
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.
 
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