An easy(ish) mod to get a self exciting ignition?

[Blurredman]

Hello guys!


After finishing work at around half 2 in the morning, you could imagine my annoyance and frustration when I found my MZ ETZ's batterie was flat! I knew that a bump start would help for nothing and likewise kicking it. I KNOW that an adequate battery is required to get any spark at all. So it was with great distain that I had to ask the security guard to jump lead to my bike's battery, where as soon as I got it started I rode and I did not stop! (luckily there's no traffic at that time in the morning eh!),


Which leads me to the fact that this fault is no doubt my one annoyance with this motorcycle, and quite possibly it's only major downside, for such a bike of it's era. I must have left the ignition in 'park' and therefore left the lights on. I have done it more than once before, but luckily not ventured too far or too long from the bike for it to have any effect, and only noticed when I got back to the machine.

Therefore, with research I know that one of the only resolutions to this is the 12V ignition kit, which quite frankly costs too much for me to warrant spending on a bike I rarely use (only using it so much now because my main bike is out of action for a little while).

The question is, is there some clever wiring that I could do that would allow the coil to get spark from the process of the engine turning over, rather than the battery.. ?


I have tried the so called 'emergency' key position for flat battery and that has never worked for me, nor my brother. Is that just a myth!?



Thanks in advance,
Blurredma

[Agronski]

Short answer to your question: No.
Long answer: self-excitation of an electromagnetic dynamo/alternator relies on residual magnetism in the rotor and/or stator assembly metal. There is no arrangement of wires that can help, only magnetism. So you have to try and polarize your stator (apply 12V directly to the field-coils for a second or two to try and force some magnetism back into the cores).

...trouble is, the MZ stator's don't hold this residual magnetism well because it's tough DDR steel, not nice soft iron (this is why the 'emergency' switch position worked back in 1979, but not today). If you really want to get a self-exciting system going, you would need to place some high-power _permanent_ magnets inside the stator, so there's always a strong field even without any current in the field coils. Problem is, the interaction of the permies with the coil's field will probably be less efficient than just keeping your battery topped up. Some MZ Rotax engines for use a permanent magnetic in their alternators, but not the ETZ.

Don't think the ETZ's have a cutout, so here's a useful circuit you could build that cuts the power to the coil when the ignition is on but the engine is not running [a major source of drain on the battery]: - http://www.edaboard.com/thread236894.html

Could also switch to LED parking/running lights to reduce the drain on the battery.

At least you can jump-start the 12V ETZ if you need to. My TS still runs at 6V, and *no-one* has a charger for 6V any more...
___

[Blurredman]

Oh well it was worth a try eh! Maybe I should just have a seperate switch for all electrics (like a killswitch but for lights too) to switch just incase.... However saying that, I've left my heated grips on my CX500 on in the past and had to get people to push me to start it. Even a light, if left constantly on when riding won't remind you to turn something off when it becomes part of the scenery.

[DAVID THOMPSON]

i put a radio BNC connector in the minus lead to the battery
for a quick disconnect of ground
did this after i had my r90 s catch on fire under the gas tank
lucky me i had a 10 mm speed wrench in my pocket
and got it out ok
dave