Intermitent ignition failure BMW r80

Guys ...this problem is caused by a faulty Bosch ignition coil (gray type). Replace both the Ignition control unit which is linked to this type of ignition coil (buy Transpo BM 300 - cheapest pattern type) & the ignition coil itself with a newer type 1990's model (red outlet points to spark leads.) & the problem will disappear. This is a known problem caused by hairline cracks in the gray casing. These cracks cause intermittent electrical disconnects when hot/wet - MICHAEL - DUBLIN - IRELAND

Hi, it's most likely to be your hall effect sensor. (bin can at the end of the camshaft). You can replace the complete unit from bmw (they say it is not serviceable) but it is quite expensive. Or if you are quite handy and patient, you can get a new sensor from farnell.com for 18 dollars and change it yourself.
First to check if the coil and amplifier are ok.
Disconnect the bin can (3 wire plug behind the diode plate)
Connect a wire onto the middle pin of the bike side of the loom.
Earth this wire to the ground when the ignition is turned to on.
If youy get a spark everytime you earth the wire, you 90% sure that it is all ok, and that the sensor is kaput!
Usually, the sensor fails completely, or when subjected to temperature (worm engine, and restart when cold).
Hope this will help, Best regards, Franck

Get a Haynes manual ISBN 1 8590 283 5
carry out the simple checks section 6.5

Google - theres quite a lot of knowledge out there.
1)"The BMW R series Ignition repair"
2) "Rebuilding a Failed BMW Ignition Trigger Unit"
3)"Ignition.htm article #30"
4)"MOTEMTRONIC IGNITION MODULE -BOSCH REPLACEMENT" on ebay About £7 pluP&P

The trigger can be repaired its fiddly, requires a steady hand, fine soldring iron,araldite, dremel or equivalent, component from RS eg RS part No 181-1441 , Honeywell SS443 = £1.11 This is a unipolar (not bipolar) latching (not ratiometric) switch.

An alternative trigger can be purchased from "http://www.jaycar.com.au/" search ZD1900 - "http://www.jaycar.com.au/ShowLargephoto.asp?id=8338&PRODNAME=HKZ-101", you need to create a log on account, order takes just over 2 weeks to arrive, expect to pay VAT and import duty, and post office handling fee still a cheap option.

connectors '3 way J.P.T. Female connector' '3 way J.T. Male connector' can be sourced at www.polevolt.co.uk

An alternative ignition module equivalent to Lucas DAB 400 Ebay"MOTEMTRONIC IGNITION MODULE -BOSCH REPLACEMENT" from Autocar-electrical.

Also check out your HT leads, the suppressor caps on my home assembled ones went open circuit. created a very weak spark.

The feed to the trigger unit is battery voltage, (but very low current, a test lead can be made to a diode not a bulb ["10 WHITE LEDs 12000mcd 5mm led led's FREE RESISTORS" goodwill sales on ebay].

Took me months to work it all out, but it don't cost a bomb.

Good luck hope this helps. {:-)

It does sount to me the hall effect sensors they are for sale in the UK at www.tamboki4sensors.eu if you send them the sensors on the plate they will change them for you for about £100 I fitted my own and they come with step by step instructions job done.

Grasping at straws here because I cant find any wiring diag / info on the net and my memory is shocking heres what I think The backfiring in the spark happening at the wrong time , So either the Ignition unit is recieving a signal at the wrong time or it detonation We can rule out detonation as it runs fine usually , just suddenly bang and stops So the ignition unit is recieving a signal , So the pick ups in the engine are in good cond, ? and the wires going to the loom to the ignition box are good in condition If it is a scr ignition unit then the gate of the scr will be recieving a signal , either through incorrectly timed pick ups , ( shorting leads of pick ups,,across terminal pins ...?? renew dodgy looking connectors and clean up earths ... ) , or the wire that comes from the pick ups to trigger the gate will be shorting ( cant remember if the gate is grounded or positive ) Which means the scr is recieving a signal telling it to release battery voltage which goes about its usual business of making a spark The coil is fine , ( you have replaced it and it still does it , So the only thing that is happening is that as you replace the coil you are moving wires .....the broken shorting wire could be there ?? Finally if you blow fuses use a winker relay across the fuse , it will cut in and out allowing the fault/wires to be fiddled with to track it down , rather than keep blowing fuses Sorry for the garbled reply , With out any info I am stabbing in the dark... all the books I have here end about 1974 .