Might be an ignition issue yet, based on this experience :-?
In the '80's a mate had an outfit on an early boxer RT, a twin row timing chain model, he had fitted a Dyna ignition to it.
Coming out of the Cane Toad Rally in North Queensland, two deep creek crossings, the bike started to run on one cylinder, and every now and then it would blow the LH carby off, sound familiar
Luckily the mate was a telecommunication technician at the time, as after a lot of grief the fault was traced to a corroded printed circuit board track on the electronic PC board that replaces the points backing plate.
On the Dyna ignition, there are two electronic switches, one opens the "points" and fires the ignition, the other closes the "points" again, the two switches are on the same circuit, so it goes "Open", "Close", every full turn of the crank.
Relative to the cam, it goes "Open", "Close", "Open", "Close", for every cam turn.
BMW use the "wasted spark" system, and fires both plugs together, every time the pistons reach TDC, one is on top of compression and fires, the other is at top of exhaust and theoreticaly does nothing.
With the track broken, it wasn't getting the signal from the second switch, and so didn't reset until the first (firing) switch is triggered again.
So for two crank turns it was going, first turn "Open", second turn "Close".
With one cylinder not firing at all, it was filling one exhaust with a nice mixture, and every now and then it would ignite, either from the hot exhaust from the other cylinder, of from the "Wasted" spark, and due to the valve overlap, would close the exhaust valve, with the inlet valve open, nowhere for the pressure created to go put up the inlet track, and when you pressurize the engine side of a CV carby, the slide is forced closed, and off pops the carby.
Does this help or confuse :-?
