Ignition Sensor – Disassembly

By now I’ve gotten used to one job leading to another as I work my way through refurbishing my ’84 R100RS.  Fixing an improperly installed drive shaft boot lead to new swing arm bearings and a new drive shaft to replace the u-joint.  Installing time-serts to repair stripped threads for the filler plugs on my bevel drive lead to a complete overhaul of the bevel drive. Installing a new rear tire lead to new taper bearings… The good news is that by the time I’m done, I’ll be pretty much familiar with every system on the bike – a key component of reliability for the long distance rides I have planned for this bike.

So I shouldn’t have been surprised as I disconnected the Ignition Sensor for easier access to install my new diode board that I found the ignition sensor connector was cracked.


This connector housing operates similarly to the ones connecting to the fuel injectors on my ’87 K100RS – it uses a wire clip to secure the male and female halves.

This connector crumbled as I cleaned it – thinking I could just glue it back together. Now it has to be replaced.  The connector appears bonded to the wire pigtail – so I decided to disassemble the ignition sensor “bean can” to see where I might best make the necessary replacement.  True to the “one thing leads to another” maxim – I’m now looking at an overhaul of the ignition sensor.  Probably not a bad idea given it’s age.

It took a while to figure out exactly what this connector is called – the most generic name I was able to find is “Junior Power Timer” or “JPT.”  While the connector on my bike was probably made by BOSCH, my GOOGLE searches seem to suggest that AMP (Amphenol) also makes this connector.  I found on-line vendors selling replacements for this plug describing it with various combinations of “Junior Power Timer”, JPT, BOSCH and AMP.

I reached out to the Airlist email list server for help, and was quickly guided to Euro Motoelectrics and Motorrad Elektrik.  Euro Motoelectrics (EME) had the part.  After already submitting an order with EME, Tom Cutter of Rubber Chicken Racing Garage also responded that he had this and other connectors available – and could even to the overhaul for me if needed.

Within hours of ordering the connector from EME – and got a personal response back from their Norman Schwab – on a Sunday!  What great service!  And since it’s Sunday – why aren’t these guys out riding?  Here’s what I ordered:

Euro Motoelectrics – ignition sensor connector

I managed to disassemble the ignition sensor with minimal difficulty.  It required using a punch and snap-ring pliers. I have the punch, but my snap-ring pliers were too large. I was still able to remove the snap-rings using o-ring picks.  This resulted in marring one of the shafts slightly – I’m hoping I can correct this with course scotch-brite and maybe a little buffing with my Dremel tool.

I found a fairly comprehensive tutorial about disassembling the ignition sensor on-line, but after scanning it, I decided I’d do as well just to go slow and work the puzzle on my own. Ignition Sensor Disassembly Tutorial


As far as I can tell, re-assembly ought to be fairly straight forward – especially after I buy a smaller snap-ring pliers. I’m guessing that proper cleaning and lubrication should be straightforward by avoiding solvents and using light clear grease.

The inside of the “bean can” cover is lined with 1/16″ cork which is deteriorating. Tom Cutter offered that he uses a light foam material to replace it – but 1/16″ sheet cork is available, so I might try that first. An Airlist message from Michael McPeak indicates that the cork lining may not have a function beyond sound deadening – and he’s seen some without a lining.  Close inspection of my part indicates that the cork extended to the lip of the cover, and also functioned as a gasket.  For that reason alone, I’ll probably try to use something.  Michaels McPeak’s message was encouraging – what a great group folks these Airhead enthusiasts are!



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