Carb Sync Tool and Electronic Ignition

[sblaylock]

I'm wondering if anyone has used the Airhead Carb Sync Adapters (Shorting Method) with an electronic ignition? Is there any risk of frying the electronic ignition using this method? I talked to EME and they were not sure if it would cause an issue.

I'm not sure I want to risk turning my expensive new electronic ignition into a blue smoke generator, so I'm hoping someone else here has tried it.

Also, is there is a way to cross post this the the other appropriate forum, or do I just need to start a new thread there.

Thanks,
Scott.

[schrader7032]

I would leave the post where it is...people that frequent the forum I'm sure look around and see anything that is new.

As for shorting, there should be no issues with the shorting method even for electronic ignition. It's important, however, to avoid open circuits as you're aware. So, make sure you have good fitting rod extensions. Then when doing the short, make the movement crisp. I would take your long screwdriver and firmly put the blade in a good spot on the engine so that you can easily rotate your hand down to contact the shorting rod. Rotate your hand away to remove the short, again keeping the blade firmly on the engine. By moving quickly you preclude allowing the spark to jump a long distance...quick movements would keep that to a bare minimum.

[palica]

I think the coils may be the victims, more than the electronic ignition.
However, I installed vacuum ports on my Dell Orto pipes from day 1 to facilitate the sync. Adjusting air/gas mix can be done with both cylinders running. It is - at least for me - much simpler and efficient that adjusting 1 cylinder at a time.
If you really matter about gas/air mix at both idle and with throttle opened, a Colortune spark plug is also a better way to do it IMO.

[sblaylock]

Thanks. I'll give it a try and see how it goes. I have vacuum ports on my R90S and have a Grok Harmonizer which I've used to set up the idle, but I have a bit of a shake at idle and wanted to go "old school", which I've had good success with on other /5, /6 bikes. Once I come off idle, it's very smooth.

Sorry for the late reply. I neglected to check the "Notify me when a reply is posted".

Thanks again,
Scott.

[srankin]

Any frying of and electronic ignition kind of depends on the system itself.

I have never heard of a problem with Boyer replacement ignitions.

I would be very cautious fiddling around with the 1981 year introduced system and any of its now available upgrade variants for pre 81 bikes. The black module is known for being fried if spark plugs are not grounded properly.

As for coils, they are tough, not much bothers them. the chances of frying a coil are slim to none unless you really try to fry one.

Overall, the electronic systems in my view are far better to have on a bike than points. St.

[schrader7032]

Actually, as 'bum says on this page:

https://bmwmotorcycletech.info/ignitiontheory.htm

ALL Airhead Ignition Systems can be damaged if the spark plug wires are removed from the spark plug with the engine running ...or the engine is being cranked or other wise operated ....if the spark plug wires/caps are not grounded properly. DO NOT have the ignition key turned on if the spark plugs are not grounded and caps attached.

I always thought it was the coil that was the most sensitive...if the plug isn't grounded, then the electrical energy is bounced back up the spark plug wire. What's the first thing it sees...the coils. The ignition system is just the switch telling the coils when the system is open or closed so the fields can collapse.

So, per him it's any ignition system. The key though is to have the plug or whatever shunt you are using be properly grounded. That's all a plug is anyway...the spark jumps the gap and goes through the body of the plug into the head. So, if you are sufficiently careful, grounding plugs should not be a problem. If you're not sure, find some other way.

[srankin]

Ok, I won't argue with Snowbum's knowledge.

A coil is just that a coil of wire wound up tight into a container. Yes, there is a chance that wound strand of wire can be burned if mistreated but, my years of playing around with coils from all sorts of vehicles to shock the heck out of friends, squirrels and such has shown me they are as I have said pretty robust.

On the other hand, the magic black module of which I have never had apart, has in it's bowels, electronic bits. In my years of messing with radios, TV's and other stuff with these electronic bits, I have found them to be in some cases very fragile.
I have tested electronic parts to destruction both intentionally and unintentionally.

ALL ignition systems can be damaged by some kind of misuse, carelessness, age, corrosion. My point is don't meddle with the Black module unless you are sure things are grounded. There is a far greater chance of something going wrong with the electronic system on an airhead than with the points system. St.

[sblaylock]

I too don't want to argue with the master, but I see Kurt's point. The ignition is triggering the coil so not grounding the plug should be an issue with the coil. Obviously the two are tied together, so maybe the lack of discharge in the coil causes upstream issues with the ignition.

At any rate, I have decided not to test this on my new, expensive, electronic ignition.

Thanks,
Scott.

[srankin]

I don't mean to argue with Kurt either, in the years I have been reading BMW forums, since the introduction of and in knowing trained BMW mechanics, I have been indoctrinated to be certain of spark plug grounding not because of damage to the coils but because of damage to the black module.

Have coils been damaged by misuse? Oh sure like I said, any system can suffer damage. It is less likely for a simple wound coil to be damaged versus the delicate module.

Oh well, to be honest, either way, you will be walking. As has been said, don't test the theory on expensive ignition systems

MAKE SURE the sparking plugs are GROUNDED before turning over with the ignition on. Bad things can happen and are more likely to happen with an electronic system than with the old points. St.

[schrader7032]

Snowbum talks about the shorting method all over this page:

https://bmwmotorcycletech.info/synchcarbs.htm

In his estimation it is the most accurate as it takes into account actual running conditions and doesn't rely on any specialized equipment. About one third of the way down that page, he makes a comparison from the old /2 engines where it was written that often times the plug cap was removed to "short" an engine. This could only be done because those engines have an alternate path to ground for the spark energy...it is through what's called the "safety gap"...it's a 10 or 11mm gap in ground points that are under the magneto coil.

So, he says that the post 1969 bikes are different. That if you create an ungrounded ignition system you can "ruin or damage coils & electronics". So he says both coils and electronics. I don't know the voltages that are pushed to the spark plugs when the coil fields collapse...is it like 40000 volts??. Can you imagine what happens when that voltage reverberates from the ungrounded plugs backwards? The coil has very tiny wires packed together...seems like such a powerful energy as that could arc across the wires, especially on an older coil, and reduce the effectiveness of the coil. If the long wind of wire is severed into smaller runs of wire, then the coil just won't produce the energy anymore.

That reverse energy first encounters the secondary winding which it can then influence the primary windings. Remember that the "brain" or electronics box is only a fancy trigger that controls the 12v that is being fed into the primary windings of the coil. It just seems to me that for this 40000 volts (or whatever) to make it back to the electronics box it has to do some damage to other things before it gets there. Can happen I suppose...Snowbum says and "electronics"...he's not real specific.

IMO I just don't see any real problems. It's like someone tells you to don't stick your fingers in the fan blades...maybe some of us would do it anyway, but basically we figure out to not do it. If you're using the shorting method, just pay attention to what your doing and I'm sure things will work out OK.