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How would you Modernize an R100RS?

Pezz_gs

Mum Thinks Im Terrific :)
I have been acquiring parts for some years, being an airhead tragic and patron saint of lost cause bikes.

I now have almost enough parts to build up a very nice modern R100RS.

1981 Frame ÔÇô Straightened - which was a series 500 Blue Silver bike. Pic below from BMBikes.

I bought it as an engine in frame & swingarm. Its engine now powers my R80G/S Dakar and does a very nice of job of it as well.
Fairing panels off Multiple bikes.
Seat and surround and sidecovers
Tank & Swingarm
R100RS%20500%20Series%20%281%29.jpg


I will build up a warm engine, hoping for 1150ccÔÇÖs. I am currently getting quotes for a billet Crank with 75mm stroke 

I would like to keep it with spoke wheels andf contemplating which front end would be best fit. An R100R front end would be nice. would even consider a R1 type front end, if I could make it fit???

I also like the Guzzi way of building a para-lever type of rear end.
2646316004_f8acc0e516_b.jpg


Anyway put your thoughts in below.
 
Start by searching and reading the many threads about this sort of thing. None of it is simple. Are you really likely to do structural cutting and welding? What's your experience with that sort of thing?
 
project

Sounds to be an ambitious project. Good luck !

What allows us to believe in the handling stability of a Type-247
is the normally minimal amount of power,
relative evenness of its delivery
and the fact that the state of chassis technology in the rest of the world at that time was worse.

Remember to think of the entire chassis as a well integrated system.
A change to any one aspect (IF that change is a significant departure from the original design parameter set)
will, without a doubt, result in the fabled "gummikuh" effect,
and amplify the shortcomings of the rest of the chassis system !

The 1150 kit, though promising "more power & torque"
seems to be gaining a reputation for cylinder distortion and a short life span.

Check out my website, ROCKERBOXER
to see the results of others who have chosen this lonely, dark, and twisty path.
 
If I were going to do something like this, I would focus on the frame, suspension and brakes to 'modernize' an airhead. So...steering head to swingarm pivot brace, maybe a swingarm brace, billet aluminum top triple clamp, fork brace, some extravagant brakes (doesn't someone make some 6 piston calipers that fit?), Ohlins shocks and find someone to perform magic on the front forks. As to the engine, I think I try a dual plug head more to see of the engine will run 'sweeter.' I don't know how much more power these things will make without them becoming less reliable or less pleasant.

Not that I've ever considered such a project...
 
beautiful bike. Enjoy what you have, it is a work of art. Any attempt to get a few more HP or performance out of this rig is not worth the $$ you have to spend.

If it were mine, I would leave it alone. That is why I have a classic airhead and an new R1200R. If I want the power, handling and brakes, I ride the new bike. If I want a great classic ride, I ride the airhead.
 
Pez:

I had a $3,500 1982 RS that ended up being a $12,000 RS. It had almost everything known to airheadkind done to it. Then I sold it for $4,000 and got an oiler RS which was three times the bike.

What I learned was to accept an airhead for what it is, and use it accordingly. If you want a modern bike, buy a modern bike.

Just my opinion. :)
 
Agree 100% with both Rinty and Tom....

I have a '78 R100RS "Motorsport" edition (aka "The White Lion") with >$11K of performance upgrades installed by San Jose BMW, including:

* $650 OHLINS rear shocks + rear swing-arm bracing
* Triple-thickness, CC Products billet aluminum triple clamp
* San Jose front fork brace
* Dual-head plugs, DYNA-III electronic ignition
* 1050cc "Blitz-Kit" / new pistons / valves, etc.
* Stainless steel brake lines, new Metzlers / Custom CORBIN seat
* Etc., etc. - - - Read more here at www.vintagemotorcyclesonline.com

At the end of the day, it is STILL a 31-year old bike and should be ridden accordingly.

NOTE: I bought the bike already completed like I described above.....

Enjoy your R100RS for what it is...and add a modern bike to the stable!

JJ Cerilli
(Pleasanton, CA)



 
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In retrospect, what mainly drew me into my expensive little exercise was a couple of things:

1. I was mesmerized by the "potential" of the RS's chassis, brakes, and engine, and;

2. the bike was just so darn good at doing a number of things very well.

And each time I signed another cheque, I reminded myself of Peter Egan's opinion that the RS is the best all around motorcycle ever built. :D
 
My vote is also to leave it relatively stock. I would go with a 13 or 14mm master cylinder, 9.5 pistons, good rear shocks, cartridge emulators in front, and convert the rear disc to drum.

Hopping up the motor only puts more stress on the trans which is the weak link and not much can be done about that. Hard acceleration might add too much stress to the tranny, so increased HP would mostly only be noticed two up and loaded, or at redline in top gear. So for normal riding, the motor will feel strong, but won't make that much 'real world' difference.

And don't go to really stiff springs in front which make for a very harsh ride. Instead learn how to ride without using the brakes.
 
My opinion,as an R90S owner, a '78 RS owner and former owner of an '85 R80 is that you just can't match the handling of the monoshock bikes with the bigger forks. You have made a nice machine. Keep it as is or sell it, but don't put money into it trying to make it handle and brake like the post '84 Airheads.
 
Having had a couple of R100RS' and being of similar mind to those who advocate leaving a good thing alone, I will say that the handling difference between my twin-shock RS and my mono RS was great. The difference between my later RS and my R100R paralever bike was another similar jump.

If I were building an RS I would not hesitate to look for a better front end with an 18" rim and great brakes. I think this is where the biggest improvement is, at least for me and it does not compromise any design philosophy or intent, simply updating in the way that BMW did with the last of their airheads...

p.s. I've not seen that silver/blue color scheme before, and was thinking about something like this for my R100R project in which I'm using a similar vintage "S" body set. Would love to see more pictures!
 
Thanks for the great replies.

Let me clarify a few things. The picture of the blue / silver bike is one from BM Bikes of the series 500 which is stated at the end of line 3 in my original post. I do not have a complete bike only various parts collected over a number of years as I said in my original post. The 70HP RS engine is now in my R80G/S Dakar

526962342_P9Dpj-O.jpg


A little about the R80G/S Dakar.
R100RS Motor overhauled 70HP
HPN 1st and 5th gears
Gold Valves in the front forks
Ohlins on the rear
32:10 Swiss R80ST Final drive (with the HPN 5th gearing is 10% taller in 5th)
310mm floating disc with 4 piston Brembo
It is the sweetest ride. :thumb

Anton: Yes I have completed many bike builds and modifications. I have a well set up workshop including a lathe, have access to CNC equipment as well. I have read a number of build threads including Vanzens and Team Incomplete which are sweet. Latest effort was grafting a set of Marzocchi 50mm Magnums onto the front of a Monster 900 trail bike build for a friend over here.

Vanzen: I am well aware of the shortcomings of the old Airheads. I will be bracing the frame comprehensively. I have enjoyed your Rockerboxer site.

Tom: I have a frame and various parts, no front forks. Some R1 Mono Bloc callipers and a lot of ideas

Rinty: Im hearing you. I have owned R1100RT and R1150GS. Oilheads donÔÇÖt do it for me. I prefer the old Airheads and I have a few. Looking at the Chassis evolution of the GuzziÔÇÖs one wonders where Airheads would be today?

Johncerilli: I used to own a BMW R100RS Motorsport, nicely modded and nice bike.

Tvrla: I am happy to tune and develop the engine. I made the mistake in the 80ÔÇÖs of buying a set of CC Products Roller Rockers. Nice looking bit of kit but once over this side of the Pacific it was obvious the geometry was all wrong. When I called Chris Hodgson he said they ÔÇÿshouldÔÇÖ be okay as they have a roller on the end. They were originally built with an offset rocket pivot but they were too expensive to make.

Mmmalmberg: go to bmbikes in the uk and look under colour schemes or do a google image search:- BMWR100RS Series 500
 
I guess I'm with the perceived majority here (unusual!), in saying that I think the better question is, WHY would you do so.
 
I've got an oilhead and an airhead RS. These are different bikes and I wouldn't try to modernize the airhead to become an oilhead-like bike.

On my airhead RS I did the following to modernize the bike -
- installed Boyer electronic ignition (the advance was slightly damaged and the Boyer was less expensive than purchasing another advance unit)
- replaced rear shocks (I purchased the Hagon units and have been very happy)
- replaced stock fork springs (I used Progressive springs) - the forks were re-built with new seals, etc.
- Almost every bearing was replaced, those not replaced were carefully inspected. All bearings were lubricated, shimmed, and adjusted as necessary, and new seals installed.
- the bodywork was fully disassembled, painted, and carefully reassembled.
- the engine & transmission was disassembled, inspected, and carefully reassembled (the updated "shift kit" was installed in the transmission).
- brakes (calipers and master cylinder) were fully disassembled and re-built. I used braided stainless steel brake lines coated with black vinyl.
- I like Corbin seats and put a new one on my RS.

When I got the airhead RS back on the road it felt like a new bike.

I wasn't looking for the airhead to make the power that the oilhead makes. I'm very happy with the reliability and "feel" of the airhead RS.
 
With the exception of going with 9.5 compression pistons, I'd leave the engine alone. Work on the handling areas that have always been a little weak, the suspension and the frame. Someone has already given details on the parts, but front fork brace, thicker upper triple brace like the CC products one mentioned, frame brace and rear swing arm brace will do wonders on the handling. If you improve the frame/suspention works, you might even be able to run some more modern tires (read higher performance). I have two RS and I like them because of the style. Nothing is better looking than an 83-84 twin shock RS. Good luck with your project.

Dave H
San Antonio, TX
 
why ?

I guess I'm with the perceived majority here (unusual!), in saying that I think the better question is, WHY would you do so.

keelerb, the answer to that question is both simple and complex.
There exists a "sub-set" of riders who enjoy tinkering, getting their hands dirty,
and a pursuit of the goal of making a machine just a little bit better –
and they will enjoy this activity even as much as riding.
The personal involvement of improving this part or that, making the bike just a little more competent, efficient,
or better suited to the individual's needs can be a most satisfying and rewarding experience in and of itself.
Even failure will be worthwhile – for the knowledge gained and lesson of learning that is a result.
I am describing an "old-school" attitude of a hands-on relationship with the machine.
A "hot-rod-mentality" that realizes the limitations of a production motorcycle designed to appeal to the masses,
and has the patience, understanding, skill set, and desire to improve that machine to better suit his (her) individual needs.
The kind of "dissatisfied" spirit which might be considered a continuation of that evolution of creative / inventive thinking
and brought to us the likes of Henry Ford, Thomas Edison ... and Max Friz.
Those not satisfied with the "status quo", having a "better idea", and working diligently to build that "better mouse-trap".
A mode of thinking that, unfortunately, as I should think,
is rapidly being left by the wayside in the face of "instant gratification", and a "mass-production / consumer driven" ideology
that thrives when we succumb to their admonition:
"you too can have the latest-greatest-fastest ... just give us your money".
It is, perhaps, one of those situations where this cliche certainly comes to mind:
"if you have to ask, you wouldn't understand."

keelerb, your question is best answered, "because I can ... I want to ... so why not !"



Imagine the loss, if you will, had Burt Munro acquiesced to that "perceived majority" ...

norman_bike_medium02.gif
 
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