(In case not everyone is familiar with the 4v K, the idle speed screw appears by magic when you twist the throttle. I now know this)
Another bright idea that came to nothing:
The 'standard' 3 spoke 4.5" rear when fitted to the paralever back end that I have used on this project, has a left offset of 2mm, with no shims fitted. I use the 2 mudguard mounting dowels on the gearbox as a datum to measure this - assuming that BMW must have put the mudguard inline with the rear wheel.
The wheel I intend to use is the 5 spoke 5" rim from a K1200. At the mo, I only have a 5.5" rim, with a 180 tyre fitted. This needs 2 shims (=5mm) to clear the swingarm. The measured offset when fitted is 12mm to the left. The visual effect of any offset is doubled i.e. things like the tail unit/number plate seem 24mm closer on the left.
Even with a 5" rim (when I eventually get one) which I hope I can use without spacers, the left offset will still be 7mm.
So I decided to see if I could offset the frame to the left by a similar amount - y'know, saw the lugs off like y'do. It would be really convenient if the drivetrain had a centre of gravity over on the left side of things too. And then I could claim that I've butchered the lugs for scientific reasons, rather than the truth, which is that I just want a fat and unnecessary back wheel.
Sooo, I did this:
Which is to say that I built up the drivetrain as much as possible (no fluids though) and balanced it on a lengthwise rod. The COG is somewhere around 20mm
right of the centreline (I forgot to mention that the 2 mudguard dowels in the gearbox align with the centreline of the OE frame - this is something I've previously measured)
There's right side assymetric stuff still missing too - the rear shock, caliper and disc, and the coolant header tank and contents. The radiator is missing, but that's pretty much central.
I was a bit surprised that it was so far off. I've all sorts of thought about this - the paralever (assymetric on the right) must be a good deal heavier than the monolever that the K75 should be fitted with. Maybe the K100 is better balanced - and sawing off the front (left biased) cylinder threw the COG over to the right on the '75? Or, maybe BMW know a hell of a lot about what they do, and this right side COG offset works out nicely with the rotation of the longitudinal crank?
Anyway, I'm off babysitting today, so the distant stare of the uncommunicative old guy in the park, won't be anything for the mums to worry about.