Running without lights or battery

[traderyoda]

My MZ ETS 250 motor is running in a race bike, so no nights.

I don't understand the 6V dynamo well enough to know what I need to run the simplest set-up. Upon dismantling it I quickly discovered it's a field coil unit, no permanent magnets. So I need to feed power to it to generate any spark. I think that I can manage that with a small battery or ultra capacitor. If I can make that work can I power the coil directly or do I still need the rectifier or regulator?

Thanks for the help!

[Puffs]

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[traderyoda]

Thanks again Puffs!

I can swap out the dynamo completely for a Vape or Tezet magneto and might have to go that way. I'd like to preserve the dynamo if I can to preserve originality. After a lot of noodling I think the machine worked by bump starting or simply hooking up a small battery to energize the field coils get going. This was designed primarily for desert racing which meant flat-out running with a pitstop or two for gas along the way. For a quick stop the stator would have sufficient residual magnetism to get the bike running again, or there would be plenty of people around for a bump start.

I have some new ultracaps around and small NiMH battery packs lying around. On the bench, it doesn't take much in the way of current draw to energize the field coils so a tiny battery is all that's needed. I'll do some noodling.

[DAVID THOMPSON]

RC plane batteries in 7.2 volts some of them have very high Watt HOURS
use a s cap and a push button kick and release button when it starts
dave

[traderyoda]

Hi David,

Yep - that's what I'm thinking. They didn't have supercaps half-a-century ago but it would be easy to hide one capable of doing this job. I have used different types and depending on quality and how well you isolate them they can retain a charge for weeks. In my case, however, since I don't intend to run the bike much it's probably easier to hide a tiny charging port in the harness and simply use the battery pack to energize the field coils. Like you say, RC battery packs would be ideal for this and their connectors are tiny.

[Puffs]

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[traderyoda]

I've found magneto solutions from both Vape and Tezet, the latter being less that half the price but seems well-designed. Right next to my Rickman MZ I have a Rickman Yamaha DT-1 with a single-coil mag/points setup that spits out a lot of fire. The mag is a simple solution and would certainly be the easiest. And certainly no one would see it behind the case cover. My only reason for staying with the dynamo is originality - I'm trying to keep it as it was and only cleaning and fixing what's broken. Rebuilding the dynamo is a simple affair. The small pack you mentioned will work fine to energize the field coils and doesn't need to stay attached. I'm fiddling with the stator on the bench measuring the residual magnetism with a gauss meter to see how it decays. I suspect that once the bike starts and runs awhile there's enough magnetism retained in the field coils to allow it to be kick-started for some time after being turned off. Since the machine was intended for desert racing where periodic pit stops were common it probably was ready to fire back up after taking on a tank of gas. At least that's my theory.

[Puffs]

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[traderyoda]

I was very surprised when I popped open this dynamo - I expected a magneto, but nope... just a field coil generator. This is a modified motor of the type used in the MZ ISDT machine. I have the original statement of origin from the MZ factory identifying it as an ETS250. Comparing it to other 1970 ISDT motors it has the same crankcase and dynamo, but the head is ported differently and it has a larger carb. I assume since this was a custom engine for a different type of racing that the factory tweaked it for higher horsepower. From what I've learned it was highly competitive and very reliable. The owner, Lynn Wineland, rode it a lot and it was a prized possession. Legend has it that he asked Edison Dye, who was in Europe at the time, to hand-carry it out of the MZ factory and get it back to New Milton where the Rickman brothers put it in a modified MkIV Petite Metisse frame. I have a Rickman Yamaha MkIV sitting right next to it and I can see the frame mods they made to fit the MZ motor. I can't wait to fire it up!

[breakwellmz]

Yours is a twin plug head like the ISDT bikes?

[Puffs]

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[traderyoda]

Yep - twin plug head.

I must say... this motor is built like a tank.

[Puffs]

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[traderyoda]

I've got my dynamo nearly rebuilt and think I have my head around it. Here's what I've learned - attached a PDF of my first cut wiring diagram. This is a 6V 60W DC+ generator with battery-energized field coils. I checked out the specs against a manual I found online (https://pic.mz-forum.com/lothar/Elektri ... ektrik.htm) and everything looks fine. I'm using all original parts except for the can capacitor - it's within spec but rather that trust it I'm replacing it with a high grade ceramic capacitor. I'm incorporating a miniature power plug in the harness to connect a battery to charge the field coils. I did some rough measurements of how long the stator's residual magnetism will last, which is a really of function of how long you supply juice. For cold-starting, a small battery pack provides plenty of energy to magnetize the stator sufficiently to get the bike running. Once running the generator sustains the field. If you run an hour or so the stator should have sufficient residual magnetism to kick-start the machine back to life for around 10 minutes. For the kind of racing the bike was designed for, racing in the desert, that's sufficient for a pit stop. In the worse case, the pit crew would have a battery along if needed. I THINK this wiring schematic will work. I have a long way to go restoring other parts of the machine but at least I have a plan for the electrics. I'll post a picture of the rebuilt dynamo as soon as I fit a few more parts.

MZ Wiring Diagram_v1.pdf

(914.25 KiB) Downloaded 231 times

[Puffs]

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