Ignition problem on 82 R65

[georgesgiralt]

Hello !
She had an intermittent problem. At first I thought it was a carburettor problem. But as the wiring was badly used and torn, I thought it was the culprit.
So I bought a new ignition harness and a motor harness because it was used too.
This afternoon I was not working so I decided to change the wiring and grease the ignition module on its radiator. As I do electronic repair, sometimes, I've a syringe of white thermal paste one use between power transistor and the heath sink. So I dismantled the module from the radiator, cleaned the old grease with acetone and put a dab of white past and re-assembled.
Engine did not start. No ignition. Not a spark. I checked the wiring, all was good.
As I have a Chinese ignition module (very bad job, made for cheap car repair ) I decided to put it on. With a spark on the head to see the actual sparks.
I had sparks but after a couple of seconds, the Chinese module started to smoke....
I thought the new wiring was faulty. So I put the old one in place. No spark with the original module, a couple of faint sparks with the "new module".
I went to a wreck car supplier and bought an ignition module designed for a Peugeot 205 GTI ... Looks the same except it is half size of the Bosch one and has no markings except "Made in Italy".
No spark at all with it and the new wiring...
So do you have any idea I could check the various modules and ascertain if they are dead or not ?
How could I check the bean can ?
Any ideas ?
I'm very sad.... I planned a ride tomorrow because the weather forecast is sooo fine ....... Won't be able to make it !

[Bob_Roller]

Here's a link to a BMW technical

site .http://bmwmotorcycletech.info/Ignition.htm


Read through it s few times, there's a lot of info there and a lot is not pertinent to the OEM electronic ignition system ,

[nhmaf]

It is beginning to sound kinda like you have a shorted coil or the wiring to the coil is compromised

[georgesgiralt]

Hello !
I think I'm beginning to get it.
Last april, I switched from the grey crack-o-matic coil to the current metallic Bosch type.
I did not switch the ignition module.
The old coil is 1.3 Ohm primary, the new one is 0.5 Ohm primary.
I may have fried the module.. This could also explain that the replacement I get from the junk yard died also. And that the Chinese build smokes...
The BMW replacement said to be designed for the "improved" coils is at 120 € a bit...
I'll try to check the bean can just to be sure and see what Mr MotorWorks or Motobins has to offer...
Sh.......

[Barry]

Georges

That might be your problem. The electronic ignition modules are different for the 1.3 ohm coils and the later 0.5 ohm coils. It's probably not just the power rating of the modules transistor that's different but also the sophistication of the  dwell control. Left to it own devices the coil would eventually pull 24 amps so there is no way in the world that a 0.5 ohm ignition system can survive without the correct dwell control which limits the primary current at low revs and also switches it off when the ignition is on but the engine is not running. Your substitute modules might have been OK with a 1.5 ohm coil but you absolutely must have the correct module for a 0.5 ohm coil.

Here is some good information on airhead ignition modules. http://www.largiader.com/articles/ignition/


If you want to understand dwell control in more depth this is an excellent article. http://www.dtec.net.au/Ignition%20Coil%20Dwell%20Calibration.htm

[Bob_Roller]

I saw this afew weeks ago on the Motorrad Elerktrik website .

http://www.motoelekt.com/ignition.htm

Can't link to a specific item on the page, but it shows the DYNA 'blue' coil and the heavy duty ignition control module .

With specific caution, that the blue coil is to be used if the heavy duty module is installed .

[georgesgiralt]

I've ordered the reinforced module at my dealer....
I've checked the bean can with the device I use to check when putting it back (a 9V abttery and a resistor and a led to see if the hall sensor switch.) and it is fine. So, I do hope the bike will run when I plug the new ignition module...
If someone has a clue as to how test the old one ?

[Bob_Roller]

If you have confirmed that the 'bean can' sensor works, if the module is good, with the spark plugs removed from the engine and laying on the cylinder, when you turn the key to the on position, both spark plugs should spark then .

That's the only test I know of for the module itself .

The power for the ignition comes directly from the kill switch, you may want to check the wire at the ignition module connector for 12 volts, it's the green wire with a blue spiral band .

[Speyman]

I had similar sounding problems on an '81 R65. I went through the whole routine; new coil (had the crack-o-matic), new module, heat sink paste, cleaned all the connections. Still had intermittent failure to start and random dying with no restart. Long story short; it all came down to the kill switch. I dissembled, cleaned and lube the switch and the ignition has been bulletproof now for several years. Might be worth a try.

[georgesgiralt]

Well, I've checked that the 12 V is present where it should be and still no spark with the old ignition module. One every 3 to 5 revolutions with the Chinese made replacement I bought as a spare... Lucky it was cheap !
Last year I cleaned the kill switch. So maybe it is still functioning properly...
I should get the new module from BMW at the end of the week. If I get it before leaving (for a month) I'll try it to see...Hope it will work !
Ignition wiring harness is new, coil is "new" (less than 5000 km on it), bean can checked (with a device containing a resistor and a led and a PP9 battery)... So .....

[georgesgiralt]

Hello !
Got the module from the dealer. Ouch !
It is not marked anywhere. No BMW mark nor reference on it. Just a dot of black paint on the cover (the style automatic testing machines put on devices when OK).
So I jumped to the bike, put the module in, connected the battery, and put a spark on the cylinder head to check for sparks. None, nope, nada, nichts ......
Crap !
Having also changed  the ignition wiring for a new BMW one (made in Slovakia, BTW...) I was wondering.
So I checked that I got 12 V at every plug I should. this was OK.  I then took the ohm meter and checked continuity from one end of the wiring to the other. This was OK.
I then decided to plug the old wiring, just to see. Bingo ! big fat mighty sparks !
SO I removed the plastic boots at the plugs and saw that the wiring at the bean can end was inverted for the external wires !
Good for German quality control !
So I re-wired it, and the bike starts. Hurrah !
As I can't exactly remember how I tester the old module I decided to put it back just to test it. It's fried. As is the Chines one I had as a replacement and smoked instantly with the new coil...
So if you buy new wiring from BMW, check correctness BEFORE using it ... I was lucky I did not fry the bean can nor the new module... Could have been worse !
Important thing is the bike is running again ! All is well !

[montmil]

It's little things like this that will drive you nutty -often causing you to buy parts you really didn't need and piling frustration upon frustration.

I recently cleaned out the under-tank master cylinder on the R100S and after refitting the tank, the engine would not start. Turn over, yes, but no fire.

A badly corroded male spade terminal, deep inside a large, plastic connector block, had failed. Bumping the tank off and on had jiggled the harness "just enough."  Even though the wire was still tucked in the terminal block, it took several hours to discover.

Oh, the joy of messing with vintage motorcycles... and cars.