BMW K bikes (Bricks)

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Dai

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Why did I do it? As a teenager I went through the usual rough'n'tumble that we had back in the Seventies and in a very short period of time - about two years - had multiple wrist and finger/thumb fractures that have left me with only half the normal movement in both wrists and both thumbs. As a consequence I always found the stretch to the switch paddles to be uncomfortable at best and in the case of the indicators, downright painful on a long run. So I decided to fit Italian-made switches as this would reduce the stretch and also make the throttle a lot lighter. One of the first things I did when I got LFB was to change the throttle bevel gears because they were nasty, notchy and took a substantial effort to twist but the (brand) new set only lasted 15,000 miles before they were as bad as the originals. I say 'Italian-made' switches because the majority of motorcycle switches today all come from the Domino SpA factory in Sitori, Italy.

I knew I'd lose the self-cancelling part of the indicator circuit but none of my other bikes have that function, so so what. What I didn't know was whether the whole idea would be possible, so I approached it with the premise that if it all went wrong, I had to be able to put the BMW controls back on with the absolute minimum of fuss. The first move was to study the flasher unit carefully and figure out where the wires went to the indicators. Once I'd found those (red/blue for left, blue/black for right, brown/yellow for power and brown for earth), I punched the terminals out of the flasher unit block and crimped flying leads to new terminals. I terminated those in a four-pin block which meant that if I needed to, I could plug the original flasher until back in with no further changes. From the other end of the four-way block I ran leads to an electronic car relay. This was screwed into one of the original holes.



I disconnected the original handlebar switches and exchanged the original plugs for new Molex ones. Here I was very careful to put large-enough plugs on so that the original indicator wires which were no longer used all had their own pins. Again, if it all went wrong it just meant crimping new plugs to the original switchgear and away we'd go with all the new wires being bypassed. The only minor problem here was that I had to add another four-way connector to pick up the hazard switch on the handlebars. I couldn't use the original 3-pin plug because the circuitry is different. I also bought a new hydraulic master cylinder for the front brakes.



Unfortunately the first attempt was a bit of a disaster. Aesthetically it was fine from the rear; the lefthand switch was off a Guzzi California 1100ie and had the choke lever as part of the switch; the righthand switch was from a Triumph 933 Sprint. The problem was that with a separate clutch lever and a separate master cylinder things got so close to the instrument panel that the levers were forced down at an uncomfortable angle.




A rethink was necessary. In the mid-Nineties Honda used to have the clutch lever pivot as part of the switch; this meant that the lever pivot would be around 20mm to the left of the separate unit now on there. A search on ebay yielded a pair of switches from a CB125T and a master cylinder from a Suzuki GSF650 that needed a remote reservoir, thus reducing the overall size of that too. Making a new brake line took about fifteen minutes and I think most of that was spent ensuring that I didn't trap braid whiskers under the olive.



The only problem I was faced with now was what to do about the choke lever. As a stop-gap (or maybe it will become permanent) I bolted the choke lever from an airhead R80/7 to the underneath of the handlebar switch. It's operable by thumb but yes, it looks as ugly as sin. A bit of black paint might fix the worst of that.




On the other side I realised I was short of the killswitch, but I can always replace the CB125T switch with one from a CB400F/500F or CB750K that does have a killswitch at a later date - if I can be bothered Very Happy . The wires are there for one - you can see where I've looped across the pins in the photo below.




Was it worth the effort? A resounding 'yes'. LFB is a lot more comfortable to ride now. As regards the control cables: effectively they are all custom made. If the clutch cable breaks, a standard one will go on. A broken choke cable isn't a huge problem as you can manually lift the lever mechanism and just have a bit of patience while the engine warms up. The throttle cable is actually a standard Honda CB250T cable with 40mm of the outer removed at the bottom. All that said, I'm still going to sit down and make a new set of control cables that I'll carry on LFB - just in case.


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'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

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