No Spark

[ipatters]

Hi everyone - just joined but have been watching!

Was wondering if anyone could help.

Have a 1981 R65 that shows no spark at all. New dual output coil, black box, leads, caps, plugs fitted. Just had "bean can" Hall effect triggeer unit checked and is working ok. Battery charger shows battery as ok, although goes flat after about 1 minute of cranking with the plugs out - not long enough, I don`t think - it`s as if there is a serious drain of current somewhere. :-/

Now for the strange bit. When I`ve been cranking the engine over until the battery goes flat and you get the starter solenoid clicking due to the low voltage, the plugs have a very good spark in time with the clicking of both the starter solenoid and the starter relay!

I`ve cleaned the earth and the positive to the starter motor. It`s as if there`s a fault with the starter circuit.
Should add that both the clutch switch and the kill switch are working correctly.

Someone has suggested putting the bike in gear with the ignition on and the plugs out and turning the back wheel to see if there is a spark - thus eliminating the starter circuit. Will try this tonight, as well as fitting a new starter relay that I have just purchased. If this works, looks like a new starter motor?

Sorry to go on, any thoughts anyone?

Cheers,

Ian.

[Bob_Roller]

Welcome Ian,

My first question would be, what condition the battery is in.

A battery can show a full charge, but when an electrical load is placed on it, it fails quite quickly if it isn't in good shape.

If you have a battery that you can remove the caps on each cell, check the fluid for it's specific gravity with a hydrometer, a fully charged battery should have a specific gravity around 1.26, if my memory is correct .

If you have a sealed battery, connect a voltmeter to the battery terminals, then crank the engine over with the starter, a good battery and starter would show no lower than 10.5 volts with a fully charged battery.

If the voltage is low, it could either be a battery that needs replacement, or a starter that needs some work (dry bearings causing excess current draw, not leaving an adequate amount to operate the ignition system).

I don't know how mechanically inclined you are, but to remove the starter and dis-assemble it clean and lubricate the bearing and sliding parts surfaces isn't a real difficult job, or if you have a local shop that specializes in starter repair, may be a quicker way to go.

There's a 'sintered' bearing, or bushing at each end of the armature shaft, and they get worn out without lubrication, and my guess is that the starter hasn't been looked at since it was built 27 years ago.

[ipatters]

Thanks for that - tried what was suggesed, still no spark. Have got another "donor" R65, will try swapping starter motors, see what happens.

Cheers,

Ian

[ipatters]

Sorry, should add that I`ve tried a good "power start" battery as a jump start - same results. Looks like starter motor problem?

[Justin B.]

First, here's how a coil works:

1.  Voltage is applied to the primary windings of the coil and a saturated magnetic field develops.

2.  At the proper time, the voltage is removed from the coil.

3.  With voltage removed the magnetic field collapses, and in doing so the magnetic lines of force cut/move through the coil's secondary windings which generates a voltage in them.

4.  There are a great many more secondary windings than primary so the voltage induced into the secondary is higher than the primary voltage proportional to the turns ration of the coil.

I have no idea what I was going to explain when I started this rambling...  But, I think it could be considered "normal" for a spark to develop when your battery ran down and things started clicking as you would be attaching/detaching the voltage source from the primary of the coil which should cause a spark.

I know this is a longshot but if you have (or have acces to) an O-scope you can back-probe the line into the ICU that comes from the "bean-can" and you should have a low amplitude (scope on the 100 millivolt scale if I remember correctly) waveform when cranking.  If you just get a straight line then there is nothing coming out of the hall-sensor.

Google Rob Frankham and BMW and you should be able to find his page.  He has a good troubleshooting chart for these ignitions.  I was thinking one of our members had edited a "Readers Digest" version of the steps and posted them but I can't seem to find them...

[MrRiden]

Perhaps I've misunderstood but I think you are saying that you can crank the starter motor for a full minute and you have no spark. As far as I have experienced the starter motor has nothing to do with spark and you could run around without one. killing the battery after a full minute of cranking seems about right and if you keep cranking 'till the solenoid clicks you will need a starter! So to me it sounds like you have no spark and that is the root of your problem. Not the starter, a starter that turns the motor is doing what it was intended to do. correct me if I'm dense.
rich
p.S. just saw Justin's post and I think he is on the right track. I would suspect a failure of the ignition module to trigger the voltage drop across the coil windings.

[nhmaf]

I am trying to follow the description of symtoms myself, and am a bit confused, I think.
But, it seems to me that you are NOT getting spark under compression conditions in the
cylinder, but you do see some spark (but which may be weak) with the plugs out of the cylinder
and grounded on the engine.   You didn't mention if the plugs were wet with gas from cranking
the engine, or if you see any vapor coming out the spark plug hole when cranking with the
plugs out.

You indicated new plugs and caps - do you have the proper resistor caps with the plugs -
what type of plugs and plug wires did you install ?

It sounds like the start motor is doing what it is supposed to do, within the limits of the battery.
If swapping a new/fresh loaner battery doesn't change the outcome, then I would rule out the battery.

[ipatters]

Thanks for those ideas folks, but I had the Hall effect trigger unit checked at Motobins with their tester and it is working correctly - how about the lead that this unit plugs into and then runs to the black box? The leads and caps are BMW items.

Cheers, Ian

[nhmaf]

I might try some different spark plugs, just to rule out the possibility that you might have gotten one or two with an internal defect or crack
which could be causing high internal resistance.   This could cause you to have no spark under compression, but might still be able to spark in open air.

Did you check the voltage at the coil primary with a voltmeter, with the ignition on, and also while cranking the starter under electrical power ?
With ignition on, you should see a steady 12V, and while cranking, this will pulse as the ICU opens and closes the current to the coil, but if it is
a digital multimeter you should still read around 10V, on average.  If you have a true RMS meter the number may be slightly less.

When you tested the bean can at motobins, was it just a basic test to see that the output changed when the vane sensor gap was passed through ?
If your spring-weights are stuck, it might be possible that the ignition timing is too advanced.   Have you put a timing light on the engine to observe
the TDC mark in the timing window while cranking the engine ?  Granted, it might not be easy to see at cranking speeds, but might at least give
an indication that the spark is being generated more or less at the proper time.

I guess that I still haven't heard if you are definitely getting air &gasoline into the cylinders either.   If, after several 10-15 second bursts of cranking
without so much as a burp out of her, if you pull the spark plugs and they are dry/without any gasoline on them I think we may be barking up the wrong tree.

We'll figure this out eventually...

[MrRiden]

I trust that you have had the "bean can" tested and all is well. The bean can is nothing more than a trigger sending a signal to the black box [AKA ignition module] alerting it to drop the voltage to the coil causing the field to collapse...refer to justin's message resulting in a spark at the plugs. If the ignition module [black box] is buggered you will not get a spark. These modules are a bit expensive but there is a way to test them if you are handy with electronics and meters. So in my estimation if the starter is spinning the engine, bean can is ok, proper leads [2K ohms!!] cols in good nick [windings not open, properly wired and reading voltage at the lugs] you have good reason to suspect the module. If the bike was run or the starter operated without the spark plug leads connected / grounded then the ignition module may very well have been knackered!
rich

[Bob_Roller]

A little systematic troubleshooting is required here, first is power getting from the ignition switch to the ICU, is there power to the 'bean can', a bit difficult to check the output of the 'bean can' to the ICU, is there power from the ICU to the ignition coil.

The wiring diagram is not very clear as to the wire connections on the ICU, I found this on the Euromoto Electrics website about the ICU.


I don't know if all ICU's have numbers molded into the area around the pins, but from left to right, the first pin number is 7, and that is the out put signal to the tachometer, next pin 6 is ground, next pin 5 is 12 volt positive input from the bikes electrical system, pin 4 is B+ which I think is the low voltage output of the ICU to the Hall Effect sensor, the next two pins 3 and 2 are  B-, one has to be a ground for the sensor, and one of them is the output signal from the Hall sensor back to the ICU, pin 1 is the output signal to the ignition coil.

I don't know if this will help any, but it may give you a place to look to see if power is present at various locations in the ignition system.

If anybody is the least bit curious about the Hall Effect sensor, here's a link to the Honeywell engineering drawing for the 2AV54 sensor, which is a replacement part for the sensor that BMW used in the ignition canister.

http://sccatalog.honeywell.com/pdbdownload/images/2av54.pdf

[thrang]

How do Ian
Welcome to the club, I guess most of us at some time or other have had starting nightmares.

Since you say your battery goes flat quickly, have you tried with another battery? The one you have might not be kicking out enough juice.