I purchased this bike - a 1994 BMW R1100R with 61000km on it last week. I picked it up in Hamilton, rode to Wellington the next day, was there for 5 days or so when I used a couple of times, then rode back to Whangarei - mostly in the rain. It ran perfectly the whole time until going past Lake Taupo when it missed a couple of times but was fine so I continued on. By the time I got to Auckland it did it a couple more times (on the motorway in the driving rain) but kept running. Then around Wellsford it cut out altogether. I coasted to the side and it started again immediately. This happened twice more but I made it home.
The next day I started it then it cut out after about 2 minutes and wouldn't start, it restarted later but the same thing... cut out and wouldn't restart for while.
The plugs have been replaced just prior to purchase by BMW dealers in Hamilton, it has Profire plug leads, full service would have included air filter, doesn't appear to be any pinched breathers. There is plenty of life in the battery, fuel is unlikely to be an issue.
I've been doing some research - and I suspect its the common Hall Effect sensor problem - where the wires to the sensor deteriorate over time and the plastic coating gets brittle from exposure to heat off the engine.
So thought I would add my research on here in case its helpful to anyone else or anyone can shed some extra light on this before I go opening up any cans of worms.
This is from http://www.bmwmoa.org/bike/tech/benc...stion_part_two
"The one element of the ignition system that has proven to be problematic on Oilheads—which also affects fuel delivery—is the crankshaft position (Hall effect) sensor assembly. In most cases the problem is not the sensors themselves but rather the problem is the wiring bundle from the sensors to the connection to the ECU. The wires attached directly to the sensors are only about two inches long. They seem to be high quality high temperature wire. The wires are crimp connected onto four longer wires that run inside a woven shield and outer bundle cover to the connection to the ECU, about two feet long or so.
The insulation on these four wires, inside the bundle, has been found to deteriorate. The insulation dries, cracks, and shrinks. This exposes bare copper wire at various points along the bundle. The damage is most pronounced where the bundle runs beneath the engine front cover and is exposed to engine heat. The damage is less often found where the bundle is located out from behind the engine front cover.
When the insulation deteriorates engine operation can be very erratic. Shorting occurs from wire to wire in the bundle. This can result in the engine not starting or operating at all. Or, it can result in the engine running, but doing so very poorly. If the shorting is from the hot wire to the signal wire from the top sensor back to the ECU, every spark tells the computer that the crankshaft is at TDC. The ECU uses these erratic signals to determine when to fire the injectors and spark plugs. Thus the injectors can squirt and the spark plugs can fire at random intervals whether the engine crankshaft is turning or not. As in many cases electrical, these conditions can appear when moisture has entered the wiring bundle and might not be present when the interior of the bundle is totally dry.
The cure for this defect is to either replace the entire crankshaft position sensor assembly (plate, sensors, wiring harness, and connector) or to strip the bundle apart and replace the deteriorated wiring with good high-temperature wire. If you are on the road, riding in rain, and symptoms occur, you may be able to cure it long enough to get home by making an opening in the outer insulation of the whole bundle near the top, under the tank, and spraying an alcohol based electrical or electronic cleaner inside the bundle. Water conducts electricity. Alcohol doesn’t. Alcohol absorbs water so the alcohol can dry it out as far as the electrons are concerned. You can accomplish substantially the same result by flooding the bundle with WD40. Once the symptoms occur you need to replace or repair the damaged assembly."
How to test:
http://www.advrider.com/forums/showthread.php?t=688232
More stories and info:
http://www.bmwmoa.org/forum/showthread.php?t=50465
http://forums.bmwmoal.org/showthread...Sensor-Failure
http://www.ibmwr.org/ktech/intermittent-cutout.shtml
http://www.bmwbmw.org/forums/viewtopic.php?f=14&t=17746
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Originally Posted by Akzle
or try to get the wiring loom on this one replaced...stand by for updates 
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. Pretty awesome that it would run at all 
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