October 4, 1996
A few folks expressed interest in my sharing some experience I've had diassembling, modifying and repairing the electronic ignition triggers found on the late model 2 valve twins. I haven't seen any of the "points in a can" units so am not sure how much of this applies to those units. Since this is pretty long I decided to post the repair section separately.
The canisters are basically simple units but some care is required to disassemble them without breaking components which for the most part are not available individually.
I usually begin removing the retaining coil and driving out the pin that holds the drive coupling to the shaft with a 1/8" (preferably 3.5mm) pin punch. Make sure the shaft is supported. I use my bench vise opened about 1/4" to drive the pin through. On some units this is a very tight fit and a press is preferred here. Collect the shims and oil retaining washer and note their orientation.
Next remove the two round head phillps screws on the opposite end along with the end cap. Remove the two cheesehead screws which hold the bearing plate in and pull the plate out.
Pull the plastic rivet out of the wire strain relief.
Extract the big C clip by grasping the tang (bent outward) and twisting it inward and out.
Remove the three cheesehead screws on the outside of the canister.
Don't remove any of the rest of the "E" or "C" rings until the mechanism is removed otherwise you risk stretching the springs. This can be done now by tapping on the main shaft while simultaineously sliding the plastic strain relief off. The strain relief can stick a little so move one piece than the other bit by bit. Collect the washers and shims that reside on the inside of the case. You may only have a single oil retaining washer on the inside.
Next carefully pry off the advance springs from the baseplate. You can leave them attached to the weights for now. Removing the top "E" ring will allow the interrupter and hall effect mechanism to be removed.
If you are simply going to alter the timing curve you will NOT have to diassemble the Hall-effect section further.
As I have posted before you can shorten the advance curve for dual plug conversions by layering shrink tubing over the weight stops. One layer will shorten the curve 2 crankshaft degrees. My experience so far is use two layers for dual plugged 336 cammed bikes and 3-4 layers for 308 cammed bikes (1000cc). 800s require less retarding so about 1 layer less in each instance will probably work. If you are going to move the point of maximum advance up the RPM scale you can lighten the weights. Pry off the small "E" rings to remove the weights. I drilled mine with 1/4" hole about 2/3 up from the pivot along with a 1/8" hole as close to the first hole without breaking through. This changed the full advance RPM from 3000 to 3500 RPM. Stronger springs would be a more elegant approach here but haven't found a source for these yet.
Reassemble in the opposite order.
Note: The drive coupling is supposed to float on the shaft. Make sure you don't accidently peen the holes over when you press the pin back in which will inhibit coupling movement.
Cheers,
Pete Serrino
'83 R100RT
This is a follow-up post regarding repair of the R-bike (2 valve) electronic canisters. Hall effect failure can be pretty costly if you have to get a new unit from BMW. The critical device is available for about $10-12US (IF you can find them). The German made units use a Honeywell/Micro Switch part #2AV54, description: "Hall Effect Vane Position Sensor". The catch lies in finding a local distributor who has them on the shelf and will sell you one or two. Micro-Switch will only fill orders of 100 or more. I was able to get a few "engineering samples" @ the $12 price. If your company does a lot of business with Micro-Switch you might follow this route. In 100s the cost is around $8US. If anyone comes up with a source for single units I am sure a number of us would want to know.
Assuming the canister is disassembled (see pt1) you get to trickiest part of the process ie. removing the vane without destroying it. The vane is held between two "C" rings and located by a pin key. Remove the top "C" ring. The key is in tight and the "C" ring between the vane and the sensor inhibits getting a pair of bearing puller jaws up tight against the shaft. What has worked for me is to place a pair of 1/4" square tool bits in the vane opening on either side of the shaft and use them as a bridge over a bench vise. Then tap gently on the top of the shaft driving it out. Watch out for the pin, it is tiny. 3mm or 3/16" music wire would probably work as well as the tool bits.
Remove the bottom "C" ring and the 2 flat head screws on the bottom of the sensor and separate the plates. The sensor is rivoted to its mounting plate. I ground mine off with a dremel and a round carbide burr. Cut the wires about halfway between the sensor and the strain relief. Cut the wires on the replacement sensor about 5/8" / 1.5cm longer than the wires left on the old sensor to allow for stripping insulation and overlapping wires. You don't want a lot of extra wire flopping around inside the canister.
Clamp the sensor lightly to the plate and peen over the rivots with, what else, a ball peen hammer. Simply resting the sensor Rivot on a hard surface while pounding will work but if you come up with a piece of steel tubing 3.5mm ID x 5 mm OD you will have an ideal staking tool. This will become obvious when you look at the sensor.
Solder and shrink tube the wires matching the colors. Make sure the vane is not distorted. A little metal work should get it back into shape if it is a little cockeyed.
Reassemble in reverse order again. Replacing the vane will be much easier than removal.
So far I have done 4 of these and all are going strong (knock wood).
Cheers,
Pete Serrino
'83 R100RT