I have what ?I think is an interesting ignition saga that others might find interesting.
Part of it is rooted in my refusal over a number of years to take my own advice - "check the basics first stupid before throwing expensive parts at the problem".
My R65 has been a frequent hard starter. Perplexingly sometimes it would start almost as soon as the button was pressed, but on other occasions I'd crank the bloody thing till the battery was near flat before it would start.
Way back in 2013 when I first reassembled the thing I chased what I thought was a simple corrosion problem and cleaned all the terminals - and it looked like it worked as for a while it would start up pretty much immediately, but slowly it got hard to start again.
Then the original ICU died due mainly to not having any thermal paste left and after fitting a generic Bosch compatible module (remember this bit, it get relevant later) it went back to moderately easy starting, which got slowly worse over time.
Annoyingly I could never isolate the problem, it just seemed that breaking and making all the connectors, loosening and retightening the earths, and a few choice swear words (I swear fluently in three languages) would always get the old tart running.
Then I fitted the 860 kit and decided to update to the late model ICU, over time I'd accumulated several of them, so you can imagine my surprise and annoyance when only one of them would fire a spark - a very generic module of Polish manufacture (again another clue if I'd been smart enough to spot it).
In the last week I decided to take the r65 to the combined restorers meeting, but, it wouldn't start.
I did the basic tests and it was a no-go, then I had a look at the beancan (which tested just fine with the stand=alone tester) and condemned it due to chaffed wiring, stuffed adv/retard and worn bushes. After a bit of a think I decided to buy an Emerald Isle unit and put the days of worn out BMW ignition cans behind me.
Today I fitted my nice new system and was rewarded with zero spark.
Gritting my teeth I tested the EI bean can with the stand alone tester and it was just fine. Next I tried the EME tester plugged in place of the ICU - NADA.
A penny dropped and I decided to go back to first principles.
First I checked the ATU connector under the front cover - it had +12 volts on the correct pin and a strong ground on the other outside pin.
I knew the bean can was capable of working and it was getting power, so what the hell was going on?
I briefly refitted the Polish ICU and was rewarded with a spark. I reconnected the EI ICU and had nothing. For testing purposes I put the Polis ICU back on, but still no spark.
I then partially removed the ICU so that I could carefully prise the boot off the bottom of the connector.
There it was, staring me in the face - one connector was standing 3mm proud of all the others. Quickly removing the ICU and looking into the connector quickly established that there was bugger all chance that it was contacting the pin on the ICU.
Counting across I determined that the pin with no connectivity was Pin 6, and a quick consult with the wiring diagram provided by Snowbum established that the open circuit was the trigger signal from the ATU.
That'll do it I thought...….
I took steps to stop that connector from ever backing out again and reassembled - the bike fired perfectly and did so with every ICU I have.
So, here's the thing, my generic 1st generation ICU and the later Polish clone ICU differ from the genuine article by having pins about 2mm longer than standard.
Which kind of explained why they worked and the others did not!
Five years I've been chasing that! And it was so simple.
Oh, and by the way the EI ignition system is fantastic.