Sunday, April 1, 2018

BMW R100RS - back on the road again

1976 BMW R100RS hits the road again.

To my shame my beloved R100RS has been off the road for nearly two years. I was halfway through a programme of minor improvements when I lost heart with it and parked the bike up with the intention to take a short rest and finish off in a couple of weeks. The weeks turned in to months...

The source of frustration was a conversion from the under tank master cylinder to one on the handlebars. This is a popular mod for owners of airheads fitted with the ATE brakes. The problem I ran into though was that the system seemed to be pretty much un-bleedable. I don't know where the issue was but no amount of pumping brake fluid through would get rid of the sponginess in the lever. The solution in the end was to give up on it all and go back to the under tank master cylinder. On reflection I should have taken that route in the first place, really before undertaking any performance mods to power, handling or brakes one should always make sure that the standard kit is in top fettle before trying to improve it.

Try your brakes indeed...

In the case of my R100 the brakes were very much not in top fettle. I had to rebuild both calipers and if I had just decided to rebuild the under tank master cylinder too from the start I would have saved myself much gnashing of teeth and workshop time all the while keeping the old girl on the road. Lesson learnt. The standard system is now performing better than any other time in my ownership of the bike, though it is still lacking by modern standards. I am not convinced that changing the master cylinder would now give much improvement event if I could get the damned thing to bleed properly...

Tyres have been changed too. On the advice of and with the kind assistance of local BMW guru Ian Clarke I fitted a pair of Bridgestone BT45 Battleaxes, 3.25 by 19 front and 4.00 by 18 rear. Handing is immeasurably improved, I went from headshakes with a fully wound down steering damper to the damper in zero position and surefooted confidence. That's not to say that handling is what you could call good, it's still a heavy 70bhp bike running narrow tyres but at least it feels a good bit more manageable than before.

It's always in the eye of the beholder but in mine this bike is
a beauty.

Final mod was a set of new shocks. Being economy minded I didn't like the price of the Boge originals or the popular choice of dial-a-rides so went for a suitable pair from TEC. The TEC ones are nice in that they are available with a chrome body and black springs to match the originals and can be tailored for rider weight and desired ride height. The big bonus is the price, just fifty quid. So far very impressed, they look and feel of a far better quality than their price suggests and out on the road the performance is good. Recommended.

So there we are, back on the road it feels like being re-united with an old friend. Great news now is that from May there is no need for an MOT and there's no road tax either. Not bad for a bike that can still run down the autobahn over the ton, just make sure you leave a good braking distance!

New TEC shocks.

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