R100RS rebuild and re-style thread.

(RIP) Kaister

Well-known member
UKGSer Subscriber
Joined
Feb 13, 2003
Messages
18,477
Reaction score
1
Location
not near to you
Not sure if i've posted this before, i don't think so - so here goes.

A couple of years ago, I bought a 1981 R100RS on a whim...everything there, just very tatty....cheap enough.

Came with a very long list of maintenance and items replaced at certain mileages so i was fairly confident it s bones were good.
Clutch had recently been done, g'box rebuilt , new valves, new diode board etc etc.

It didn't have a battery - so i couldn't ride it but it fired up off some jump leads ok.

It has a full staintune stainless headers and silencers on it - which is nice.

I had factored in a full rebuild anyway for the price, so i wasn't caring what was going on, if i'm honest.
 

Attachments

  • DSC_0221-sml.jpg
    DSC_0221-sml.jpg
    210.3 KB · Views: 823
Work started immedeately on pulling it apart...No horror stories, all the fasteners came apart easily...all seemed to be genuine BMW stuff too.

The paint on the frame and engine was probably original and very tatty
 

Attachments

  • P1290973-sml.jpg
    P1290973-sml.jpg
    218.3 KB · Views: 791
  • P1290975-sml.jpg
    P1290975-sml.jpg
    213.5 KB · Views: 795
....aaaaand here it is ...the latest update.( i keep forgetting how to upload pics from google photos and get bored ... :)..)

Here in Austraay-lya we can still buy paint stripper that actually works...so i got started on the tank....it was very poor paint.

This bike was obviously a long distance machine as it was just tired out, certainly not cosmetically looked after.
 

Attachments

  • tank.jpg
    tank.jpg
    222.5 KB · Views: 416
so we have a new rear stainless mudguard and uk style rear tail light filed and modified to fit the rear subframe loop.

Single police issue seat from somewhere in Germany and a spray paintedengine in silver.....

Tank is shown in bare metal.
 

Attachments

  • bmw5.jpg
    bmw5.jpg
    60.8 KB · Views: 319
er...why not ?....it was dirty and not coming out of the frame so a bit of paint livened it up visually a bit.

standard RS bars and fairings are very 'Autobahn' oriented. Here in Austrlia its ver hot and speeds are much slower - hence the proliferation of cruiser style bikes here...Fairings are gone, Low bars gone and these bars are going to be used....a bit GS like...?
 

Attachments

  • bmw6.jpg
    bmw6.jpg
    43.9 KB · Views: 263
I looked at lots of rear suspension options and initially i was going to use Hyperpro. However, bearing in mind this bike is only going to be gentl used, I decided on a cheaper alternative. Having never seen any or knowing anthing about them, i ordered some cheap shocks from Alibaba using the calcs on the site for spring rates.
When they showed up, i was pleasantyl surprised at the outwards appearing quality of the finish. They may be awful to ride on,( they aren't ) but time will tell.
I ordered them 25mm longer than standard to give the bike a bit of a lift.
 

Attachments

  • bmw7.jpg
    bmw7.jpg
    23.9 KB · Views: 261
  • bmw8.jpg
    bmw8.jpg
    50 KB · Views: 259
So now we have new grips and levers fitted - headlight fitted using alloy ebay holders, seat and shocks and guard all working in close harmony.
All BMW parts ordered from Moto bins in the UK - minus 20% VAT removed..:)

As you can see the new shape is emerging....
 

Attachments

  • bmw9.jpg
    bmw9.jpg
    50.6 KB · Views: 293
It round about this time of the build i spotted another reason the bike was a bit cheap....:eek::eek:
 

Attachments

  • frame.jpg
    frame.jpg
    215.7 KB · Views: 279
As you can see the frame had cracked just under the headstock stiffening gussets...right the way round, not just a crack.

Also around this time i'd finished stripping the tank and found lots of brazing along the left hand lower seam - the side of the sidestand. In Australia in the 80's and 90's the petrol was allowed to have more water content so the water always ate the seam on the LHS lower and rusted it out. Good used BMW airhead tanks are rare over here for this very reason.

I checked it for leaking and sure enough it was....not too happy.
After a bit of searching i found a mobile welder - called 'Fiddlywelds' who assured me he could fix it all up.
We ratchet strapped the frame together while it was welded and the tan was purged with water and compressed air blowing through it
Frame Tig welded and Tank Tig welded - all good
 

Attachments

  • frame2.jpg
    frame2.jpg
    219.8 KB · Views: 259
  • tank2.jpg
    tank2.jpg
    221.7 KB · Views: 284
  • tank3.jpg
    tank3.jpg
    217.1 KB · Views: 274
As you’ve said,it’s not just a crack,the frame has snapped.
Never seen that before,not in that spot.
Feal sure you have investigated to a degree,but why do you think it’s broken like that?
I’ve seen headstocks bent with buckled plates,fracturing due to internal corrosion .
Think I’d chuck it in a skip.
No available s/h frames ?
 


Back
Top Bottom