It’s a 1996 RT, without the enormous fairing. A large improvement if you ask me
My favourite way to get a main feed from a BMW Boxer: slip a fat red wire under the positive battery lead on the solenoid
Denis has gone for a new ignition (the blue thing), and new diode board (the green thing)
New ignition switch fitted in the central hole normally occupied by a BMW logo. Brass nut, made from an old tap fitting, is by the wonderful Steve Baker at at Q Prep
Without the fairing, many of the original connector plugs had been on show. To improve the look I moved all the front connections into the headlamp shell
Denis’s 1996 BMW R100RT
Denis is understandably fond of this old thing. He bought it without the fairing, so we may as well call it a straightforward R100.
It was all running quite nicely when Denis contacted me, but the loom was a bit tired in places and he wanted to get it renewed, as he put it,” to prevent any wiring gremlins in the next future days of the bike”.
He had already fitted an aftermarket Wedgetail ignition; new coils, leads and plug caps; and a high-capacity (400 watts!) Enduralast alternator.
The electrical design on the R series is more like a car than a bike. Relays for everything, minimal fusing and a lot of external splices (as opposed to internal splices, which are the little blobs on the wires in the diagram).
My approach is to do what Honda did in the 1980s: add fuses for all the main circuits, hide the splices inside the loom, and only use a relay when you have to.
Doing this takes a lot of time, thought and fabrication of special brackets. It can seem as if the whole bike is fighting you.
For example, Denis had bought a new battery for the RT, a huge 30 amp hour device. But the original BMW battery straps didn’t fit.
After some research I realised that 1990s RTs came with a normal battery and a monster option. The battery carrier on this bike was for the ‘normal’ size. Once I’d sourced one (from Tayna, as usual), the straps fitted. But I still had to finesse the terminals to get the cables running nicely. It is amazing how long an apparently simple job like this can take.
The Wedgetail ignition was another puzzler. It came on a big aluminium plate that didn’t fit. To accommodate it, I ended up repositioning almost all the components along the right side of the frame. The original relay and connector block carriers were little help.
The original ignition switch was shot, and Denis had discovered that a new one was about £150. This seemed a bit steep, so I suggested he get another one. He found a BMW switch from another model. The previous switch (moved from the RT fairing) had been glued into a hacked-out hole in the console, so we got a new console and thought about a better solution.
There was an ideal place: the hole in the middle of the console, with a BMW logo clipped in. I made an aluminium surround to locate the switch in the console, but we still needed an M22 x 1mm pitch retaining nut. My lathe isn’t up to that, but Steve Baker at Q Prep in Oundle made one in record time. I’ve said it before, and I’ll say it again: Steve is a brilliant machinist.
The loom build itself was a breeze, and the bike started very happily. I hope Denis has many enjoyable miles with his sorted R100.
This might look like a normally installed battery to you, but it didn’t start out like that
I had to go to some length to get the battery leads and retaining strap to fit well
From left: repositioned flasher unit, fuse box, regulator, ignition amplifier, coil and relays. Plus one of the new twin Fiamm horns
These things have such amazing engine balance, and are so soothing to ride. They are worth all the effort it takes to keep them running
