No spark WTF!

[Rapid Dog]

1981 R100RS....

...so after cleaning all the contacts on the bike, getting the carbs sorted it starts and runs great, better than ever with the new idle needles I replaced. Still a little popping, anyhow...

I come home after a warmup to synch the carbs and shut it down.
The battery is dead...O.K., so I put it on the charger for an hour.
Go to start it up and WTF, there's no spark!
I checked both sides and no spark at the plugs.

I haven't the foggiest...bean can took a shit?
It's got a new one per the PO.
I replaced the ICU myself.

I also just went thru the gauge cluster and replaced a bulb. But the only lights that work are OIL and HiBeam.
Now the tach doesn't work either.

[ME 109]

Check the connection of the earth wire (brown) that connects to the left hand coil mount.

or

Has the left hand coil broken from the mount?

[Sunbeem]

Was the ignition inadvertently left on while you charged the battery .................?
Nah .. it's only me does stuff like that.
Better advice will follow.

Sunbeem.

PS. Was the tacho working last time it ran ?

[Rapid Dog]

Yeah, tach worked fine last time I rode it. i think part of the problem is the 'iffy' flexy board in the gauge cluster. I had some soldering repairs made. Since only the HiBeam and oil light work and nothing else it's gotta be FUBAR. I have a new flexy coming.
That said, I failed to remove the battery ground before charging. I used a SEARS 2 amp charger. I did flip it to 10 amps once for a few seconds...not sure if that may have fried something

Abyhow, I need to know how to bench test a bean can...

[Rapid Dog]

Check the connection of the earth wire (brown) that connects to the left hand coil mount.

or

Has the left hand coil broken from the mount?

The bike has new brackets and new dual plug Dyna coils. I wondered about the brown wire.
Should that be on bare metal? It's grounded at the bracket screw on the left coil, but there was some painting that went on before I mounted it. I did remove some of the paint with a sanding block at the bracket boss.
Maybe I need to really take it down to metal?

[Garnet]

Should that be on bare metal? It's grounded at the bracket screw on the left coil, but there was some painting that went on before I mounted it. I did remove some of the paint with a sanding block at the bracket boss.
Maybe I need to really take it down to metal?

It is good practice to run an aditional wire from that harness ground point to the - side of the battery or to the same bolt on the trany that the battery ground cable goes. I don't think it has anything to do with your current (pun) problem, but it will fend off future chraging related isues.

[Rapid Dog]

I did the ICU test and it came up with no spark, meaning the (NEW!) ICU is bad according to the link below.
I'll throw it in the box, but I don't think you like what you see.

Here's the Test:
The following is from a link at BMWMOA; http://maniac.deathstar.org/~flash/ig_trig.html

"
(Note: the following paragraph of trouble shooting methodology is straight out of the factory manual.)

If you have NO spark, a dead pickup transistor is easy to diagnose. You can verify that your ignition AMPLIFIER is operational. If the amp is good, then the trigger unit MUST be bad.

1. Unplug the connector between the trigger unit and amplifier. (See instructions for disassembling connector below.)
2. Stick a pin in the AMPLIFIER'S connector, center pin. That's the connector coming from "up".
3. Remove ONE spark plug from the head, stick it back into the ignition wire, be sure the ground portion of the plug is in good contact with the head and you can SEE the spark gap.
4. Everytime you ground the pin sticking out of the amp's connector (with the ignition operational and on) you will get a spark AT THE SPARK PLUGS if the amplifier is good. In that case the problem is probably your trigger unit. If you do not see that spark, then your problem is NOT likely to be your trigger unit. Fix that problem first, then deal with the trigger unit IF necessary."

[Rapid Dog]

It appears I was wrong about the ICU it is good.
So, I need a beancan (12111244088 IGNITION SENSOR)
if anyone has one to sell...
__________________

[StephenB]

Check the connection of the earth wire (brown) that connects to the left hand coil mount.

or

Has the left hand coil broken from the mount?

The bike has new brackets and new dual plug Dyna coils. I wondered about the brown wire.
Should that be on bare metal? It's grounded at the bracket screw on the left coil, but there was some painting that went on before I mounted it. I did remove some of the paint with a sanding block at the bracket boss.
Maybe I need to really take it down to metal?

This brown wire doesn't "ground" the coil, it is in fact the frame grounding point for the electrical system, just like the battery and tranny ground wires. The coil doesn't need ground to its external case to function. If the threads on the coil bracket are metal (not paint) and the underside of the bracket screw and the ring terminal ring are clean and metallic, it will provide a good ground. The malfunction of your ICU can be ground related.

[ME 109]

Quite right Stephen about the coil earth requirements.
My thoughts were that as this wire may have been removed for cleaning etc, it may have been causing the symptom described.
My left coil once broke off from the frame, taking the brown wire with it.......
Instant loss of engine electrics.