No spark! Why?

[baldwithglasses]

I was riding back from Florida the other day, and the bike ('82 R65) started acting funny. The motor cuts out, but the lights are still on, starter kicks, but no spark.

I pull off the road, wait a few minutes, bike starts up again. Hours later, it happens again, except this time the bike has to rest longer to start back up. Again, the starter turns but it desn't fire.

Am I looking at a coil failure or at an ICM failure?

I know the coil can be swapped with a Harley/Buell substitute, but what about the ignition dingus?

Didn't I see somewhere a viable substitute for our beloved Airhead's ignition control module? That is, another option besides the expensive BMW module?

[beemer]

Mine did the same thing some time back,it was the dreaded cracked coil problem,i changed mine with a coil from a K100,and made a mounting bracket so it fitted in the same location as the old cracked coil,the bike has been fine since,good luck.

[Andy-Gadget]

After you have tried to start the bike, does it do the boxer "chuff" when the key is turned off?

If it does, the problem is most likely in the tin can, if it doesn't "chuff" the problem is most likely in the coil.

The reasoning for this lies is the source of the "chuff".
Coils fire when the magnetic field collapses, it doesn't just disappear, it collapses.
They don't fire on points closing due to a thing called self inductance that means the magnetic field builds MUCH slower than it collapses, the coil acts as an inductor.
It is this collapse that generates the high voltage that actually fires the plugs.
This is why points systems fire when the points open, not close, the electronic system just replaces the points with an electronic switch that is controlled by the triggers in the tin can.

When the key is turned off, it kills the power to the coil, causing the field to collapse, firing the plugs where ever the engine is.

I am in the pleasant situation of having lots of spares, so I would just keep swapping until it came good.

If it is coils, can I restart the coil replacement thread with my solution, again, Bosch GT40T coils in parallel.


If the old coils is this colour, change it regardless.

[montmil]

Yo, Baldy

If you're still running the OEM Crack-O-Matic ignitiom coil, pull the tank and inspect the coil for tiny -really tiny- cracks. You may need to clean the item first. Cracks can be longitudinal or on the ends, often a circular pattern.

Rick Jones will send you a Dyna coil for your bike. I have them on both my R65s. http://www.motoelekt.com/index.html

Could be a heat-related failure of the Hall sensor in the Ignition Trigger Unit, aka, Bean Can. This could be near impossible to troubleshoot as it is a random failure you're experiencing. However...

There is a simple check to confirm a total failing of the sensor.

Pull both spark plugs, reconnect leads and lay the plugs on the cylinder head/s. Ignition key ON. Toggle the right-side bar "kill" switch. You should see a spark at the plugs -both plugs, as the system is a wasted spark design- if the coil is good. No spark is a bean can failure.

As I mentioned, this may not be beneficial to you with your intermittent problem, but the checks and tests will get you started.

Monte

[Bob_Roller]

As an alternate to the $129 OEM BMW ignition control module, the part with the heat sink bolted to it.

Motorrad Elektrik (Anniston,Alabama area), and Euro Motoelectrics (Denver, Colorado area), have non-OEM substitutes for $60, and $45 .


http://www.motoelekt.com/

http://www.euromotoelectrics.com/

Part number for euro moto is: IgnModR1

Also, at least on some versions of the ignition control module, the heat-sink is removable, and there is supposed to be a grease like compound, called heat sink paste.

Available at electronics stores like Radio Shack .

If that compound is not there, it is possible the unit is getting hot, and giving you an intermittent failure .

If the Hall Effect sensor in the 'bean can' on the front of the engine is failing, it will cause the same intermittent ignition cut out.

If you can simulate the heat conditions by applying heat with a low heat source, a hair dryer, as opposed to a heat gun, you may be able to duplicate the failure without riding the bike .

A can of spray freeze to rapidly cool the part after you get it to fail, may help you to isolate the problem part .
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[baldwithglasses]

Thanks, guys.

[montmil]

Good call, Bob, on the heat sink paste. I forgot 'bout dat even though I've recently refreshed both the R65's.   Monte

[Yikes]

Had the same problem with my bike and it turned out to be sensor in the bean can.  It was an occasional problem that happened more and more frequently.  At first, after a few minutes wait, it would get going again, but after a while, once she stopped, there was no getting started.  For a while, I could get her going again by swapping out the battery with another fully charged battery, but after a while, riding around with a second battery in my saddlebag, even that stopped working.  

A tellale sign (as I now know) was the that the tach would drop to zero as the bike was stalling, even when the revs were up.  A used can from an R100RT off of ebay was a straight replacement.  Not cheap, but an instant fix.  I just got a replacement sensor thanks to Rob Roller, to repair the original for a spare.