12 volt conversion

/2 BMW electrical 12 volt upgrade, Mz-b, motorrad Elektrik, magneto, generator


A collection of info on electrical upgrades to the /2 BMW motorcycle.

As you will see, these are old emails, as are the prices shown.  Collected emails by Allan Atherton and posted here as a convenience, thanks, Allan.

Comparison of 12-Volt Conversion Systems

Wolter Klaus , 14 Mar 2002

The mz-b system http://www.dynamo.mz-b.de/bmw/bmwmain.htm

-Vech’s system replaces the 6v generator with a 12v alternator.  The MZ-b system replaces the 6v generator with a 12v alternator AND it replaces the entire ignition system.

-Vech’s 12v conversion system is 200 watts while the MZ-b is only 150 watts.

-Vech’s system uses a true alternator, where the current through the field controls the output of the alternator.  The MZ-B system uses permanent magnets for the field so they have to regulate the higher current from the stator windings.  Basically, the regulator is controlling less than 4 amps in Vech’s system while the regulator in the MZ-b system is controlling up to 11 amps of current.  (150W / 14v = ~11A)

-Vech’s system does not affect the (Bosch magneto) ignition system that came standard on the /2.  The MZ-b system replaces the ignition system.  With the MZ-b system, you remove the entire magneto system: Coil, points, points-plate, rotating magnet, pole-piece, condenser and mechanical advance.  The MZ-b system uses a dedicated winding, located in the alternator, for their ignition system.  They replace the mechanical advance with an electronic advance and the coil is similar to the coils you find on newer cars that use a wasted spark ignition systems.  The MZ-b system will run fine without a battery in the bike.  (They suggest you put a small capacitor in its place if you do not install a battery.) It’s a modern magneto ignition system that uses electronics to replace the breaker points and the mechanical advance.

-Vech’s system is all contained neatly inside the engine covers.  The MZ-b system hangs stuff outside in the breeze to avoid the biggest enemy to electronics: Heat.

-I’m not sure how well the connectors, used to plug the various modules together, in the MZ-b system would survive out in the elements.  They don’t look to be as moisture-proof as what you see under the hood of a modern car.  I could very well be wrong on this, however.

-It should be pointed out that MZ-b uses Vape electrical parts in their systems.  MZ-b specifies the timing curve and does the packaging, marketing, and distribution.  I have no idea who makes the basic alternator assembly for Vech.

-Both systems can be converted back to “original”, should the desire arise.

From: “Wolter, Klaus”

Date: Wed Feb 5, 2003, 2:28 pm

Subject: RE: [slash2] Re: 6v battery and the MZ electrics

Your Motorrad Elektrik alternator conversion kit is more conventional and is just like what is used on most cars.  The ignition coil that comes with your MZ-B 12v electronic ignition conversion is not the same as the ignition coil that comes with the system that includes the alternator.  Your system is dependent on the battery being able to supply enough current to fire the spark plugs when you try to kick it to life.  If your battery is dead, there will be no spark.  This is not the case with the MZ-B system that comes with the alternator.  Your Motorrad Elektrik alternator is not very similar to the MZ-B alternator.  Your alternator has no permanent magnets, like the MZ-B.  The regulator on your alternator controls the charging current by controlling the intensity of the magnetic field, inside your alternator, electrically.  The MZ-B can’t change the magnetic field inside its alternator.  It’s fixed because it uses magnets instead of an electromagnet.  Magnets, in the MZ-B alternator, allow it to generate a spark without a battery, just like the original BMW ignition.

From: Joel Rapose

Date: March 8, 2017

Hi Duane

My e-mail address is joelrapose@frontier.com  my website is  www.rapose.biz

I can not sell the kits for what the factory in Berlin sells them for as German postage has gone WAY up, plus now UPS charges me a handling fee.  I now have to go thru customs and there is a charge for that.  Everyone gets a bite out of me.  I have to collect sales tax on every kit I sell in California of 7.25%.   I have started selling on eBay some, but those kits are more expensive as eBay fees have gone up.  I am happy to sell direct, and home pickup is always welcome.  I stock roughly 20 kits at all times, for even the singles and really early bikes.  Delivery is usually 4 days or less, as I use Postal Priority Boxes.  I accept PayPal and pay the charges.  I include the alternator puller and the voltage regulator mounting plate in the price of the kits.

The new kits (basically all I sell) have everything mounted under the front cover with the exception of the voltage regulator which sits just aft of the fuel tank, for cooling.

I am always happy to help with technical advice or installation questions.

Thanks,  Yer Pal


Note by Duane, it takes far longer than 2 hours to install the Mz-b system.  Joel and I did one together and it took us just over 2 hours.  One also needs the 12-volt bulbs.