Spark

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Hi
I've had my 1982 R65 off the road for a couple of years I'm putting it back on the road and seem to have a bit of a weird issue with the spark. There is no spark when turning over the engine but every time I turn the kill switch off on the switchgear I get one spark at the plug, the battery is well charged and the bike was running fine when it was layed up. When it's being used daily it's always been a good starter but if it wasn't used for a couple of months it's always been a pain to start.Any pointers as to where the problem may be will be greatly appreciated.
Thanks Tim

[Bob_Roller]

I would check the ignition coil, the factory put in black and gray coils on the early bikes with elctronic ignition systems, '81- 84 model year bikes .
It's commonly referred to as the crack-o-matic coil, it develops cracks in the case, this usually causes issues in damp or wet conditions .
If you see no cracks, check the primary and secondary circuits of the coil, the primary should be around 3 ohms, the secondary around 11-13,000 ohms .

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Thanks for the reply, one of the coils packed in a few years ago and they where swapped for a dual output coil, apart from now it was the only time the bike let me down
Tim

[Bob_Roller]

BMW introduced an upgraded ignition coil in the late '80's-early '90's .
It's red and black, I replaced the gray and black coil in '94 when it failed, installed the upgraded part and it failed 8 years later .
I went to an aftermarket coil, DYNA ' brown ' coil .
There are other aftermarket coils that will work  .

[Bob_Roller]

I made a mistake, the primary circuit of the coil should be 1.5 ohms, not 3 ohms .

[Tony Smith]

Ok I don't think you have a problem with the coil, or at least the coil is not what is causing the "un-start" condition.

Interestingly the fact that you get a spark when you toggle the kill switch is a big clue as to where your problem might be. In fact, toggling the kill switch is the preliminary test procedure that tests the coil and the ICU. This means that your coil is capable of producing a spark and that the ICU is powering up the coil.

My suspicion is that the problem is the trigger circuit, i.e. the (in)famous beancan. My first port of call given how long your bike has been off the road would be to remove the engine front cover (disconnect the battery first) and then carefully open the connection block in the cable from the beancan to the ICU. Beware this connector block becomes fragile with age and will shatter like fine glass if you force it. Carefully prise the wire bail out first and then separate the connector - spray contact cleaner in there and look to see if there is any corrosion on the male part of the connector - if so a nail sanding block can be used to carefully remove it.

If the above does not restore your spark, the next (and sadly unlikely) cause could be loss of earth under load. Near the relays you will see a screw connecting a large number of wires to the frame of the bike - remove the screw, clean and terminals and replace.

If the above doesn't restore spark I would strongly suspect that the hall effect transistor in the bean can has "gone to God".

Your last move before spending money would be to see if there is a local BMW owner who is willing to put your coil and your ICU in their bike - if their bike still runs, start saving for a beancan repair.

[mrclubike]

I agree with Tony
More than likely your coil is fine

Like he said check your wiring and connections visually   

If you can read a schematic and know how to use a VOM
We could tell you what to check
But I am not going to sit and type out all the checks if you can't     

More than likely it is the bean can or the ICU

If like Tony suggested and you cant find some one to test your parts on a running bike

I would start with a new ICU because they are cheap and it isn't a bad idea to carry a spare with you anyway
But you may have to make an adapter to mount it because they changed the spacing on the mounting bolts
and the adapter the sell   will not always  fit your frame

If the ICU doesnt fix it I would suspect the bean can

If you   want to you can rebuild the bean can and  install a new hall affect sensor yourself
The are relatively cheap
 

Or buy a remain from MOTO-BINS

[mrclubike]

 If you ICU bracket looks like this
The adapter they sell will not fit
This is a picture of my 82 R65 and the adpter does not have any place to bolt because the mount is welded to the frame

[mrclubike]

If you have a bolt on bracket like this then the BMW adapter will fit

[mrclubike]

Here is the adapter I made to fit the new ICU
It is a very tight fit so you will need to get it as close to frame as possible and file the ears down on the new unit so it does rub the fuel tank

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Thanks for the replies
The bikes in friends garage and I won’t be able to get to it for a week or two, but as suggested I’ll start with the connections and work on from there, I havnt another bike to check coils and ICU on but after a quick google search I reckon I’ll be able to do a few basic tests on the bean can. Again thanks for the all the info and I will get back to you and let you know what it was when I’ve found it.
Tim

[Tony Smith]

If you are handy you can make a beancan tester for about GBP5 including the 9 volt battery to power it. a bit more if you insist on fitting a junior power timer socket to the tester - they are about GBP7 all by themselves.

I'll have a quick look for the circuit forthe bean can tester and if I can find it in 5 minutes I'll post it.

[Tony Smith]

here it is

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Thanks Tony
If it isn’t a bad connection that will be my next step
Tim

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It was the bean can, now replaced and running well
Thanks tim