All entries for Sunday 25 November 2007

Fitting heated grips to an Airhead GS is far from simple. At the end of each grip a wire protrudes from the conductive material, extending down the inside of the handlebars to emerge from a small hole at the base. The first challenge then is to get the wires to follow that route, and to pull them out of the awkwardly small hole. The solution is to tie the wires to a semi-rigid length of gardening wire (the sort used to tie plant stems to supporting sticks). This can then be threaded down the bars, and pulled out through the hole using tweezers. Using bright coloured wire maked the job a little easier.

That’s all fine when using the standard BMW hand guards. However, the standard guards offer very little crash protection. For off road riding, where broken fingers are always a possibility, rigid guards are necessary. Acerbis offer the best of these, with a strong plastic strut attached to the bars and bolted into the ends of the bars. That’s fine, but completely incompatible with BMW heated grips. The bolt at the end of the bars leaves no space for the grips’ wiring. And so Touratech offer a modified set of Acerbis guards, each with a bolt that is flattened off to accomodate the wiring.

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That is not. however, a complete solution. It is still necessary to cut out the rubber and plastic cover at the end of the grips. The throttle side grip gives a further challenge. It must be able to rotate as the throttle is opened and closed. As the grip rotates, so does the wire. Twist the grip too far, without having the flattened bolt in exactly the correct position, and the wires are cut cleanly apart.

This has now happened to me four times. The throttle grip costs £50. An expensive way to warm my hands. When the wire does get broken, only small stubbs are left within the grip. An effective repair therefore seem impossible. Or rather seemed impossible. Fellow GS rider Martin, it transpired, is a genius with a soldering iron. Within just a few minutes he managed to re-attach the wires to the barely visible stubs. The weld seems quite strong, and now that the grips are back on the bike, it all seems to work correctly.

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But how can I be sure that they will not break again? Getting the flattened off bolt in exactly the correct position is a good start. I have worked out a technique: put the bolt into the grips; tighten the bolt lightly, and twist the grip around so that the bolt is pushed into the perfect position by the moving wire; then tighten the bolt. It seems to be effective.

I might also refrain from winding the throttle on full; such heavy-handedness has no effect on the acceleration of the lumbering old airhead anyway.

Now I must test it in two ways: 1) ride on a cold day; 2) fall off on a dirt road.

You might recognize this from the classic German war film Das Boot. This ancient BMW design would appear to have been copied from the engine room of a 1940’s U-Boat.

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On the starboard side I fitted a standard BMW cover, in plain unpainted alluminium – or so they claim. Just one of these small components seems to weigh over 1KG. Perhaps then it is true: air-head boxer engines were hewn from solid granite by an army of elves somewhere deep in the Black Forest.

And on the port side I now have the modified Touratech cover. The standard oil filler on the airhead is placed behind the carburettor. With the big 35 litre fuel tank fitted, adding oil required a funnel with a long nose; not really the kind of thing one would want to carry on an expedition. The engine sips oil steadily, and so a better solution is required. With this modification, I can add oil easily, without a funnel. The oil then quickly drains back into the sump through the push-rod tubes.

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A great idea. I’m sure that every airhead GS owner would want one. Unfortunately, Touratech UK told me that I just bought the last one to be made.