my specialty:12volt conversion kits for BMW /2 motorcycles



Congratulations on your new 12 volt conversion kit. I'm sure you will be delighted with this significant upgrade to your motorcycle. The photo above shows a friend's 1966 R69S after the installation of a PowerDynamo kit. All the 12v components are out of sight behind the front engine cover or tucked under the tank. No extra wires run to the headlight--the bike looks completely stock. The difference you will notice is how much easier the bike starts and runs, and a much improved lighting system..

To assist you during the kit installation process, this web page documents an actual installation of a PowerDynamo (formerly MZ-B) 12-volt upgrade kit. PowerDynamo makes conversion kits for a wide range of classic motorcycles and the factory instructions that come the kit are general in nature, lacking in the detail that might make a novice owner more comfortable installing the kit him/herself. As you will see in this section, the installation is straightforward enough that you can do it in an afternoon without the service of a professional mechanic.

PowerDynamo recently made a number of significant improvements to their 12 volt conversion kit. It's a great system, for some reason the factory does not include in the kit everything required to install the 12v system on a BMW /2 machine. I add these required items to the kits ordered from me so that you have everything in hand that you need to install the PowerDynamo 12v conversion kit on your BMW. You will need only some common hand tools and the use of a timing light to make the initial ignition timing setup.

IMPORTANT: The instructions, comments, and photographs in this section are designed to compliment and amplify the factory installation instructions. What follows on these pages is an actual installation that Tandy Bozeman and I recently accomplished one afternoon on his 1966 R69S motorcycle. I am confident that the photographs and installation description offered in this section will make your installation experience more enjoyable. However, the printed installation booklet that comes in the box with your Powerdynamo kit remains the primary source for installation instructions. I suggest you read over both the factory instructions and the information on this web site before beginning the installation, paying particular attention to the "Important safety and operating information" on the final page of the factory instruction booklet.

Remember if you have questions or difficulty, I'm here to support you--mail me at JoelRapose@frontier.com or if you're in a crunch give me a call at 530-259-3150. I would also appreciate any comments/suggestions to improve this section.

Joel Rapose

Okay let's get started:

The photo below shows the items you should find in the factory box:

kit box contents

Top Row L/ R: (1) wiring harness; (2) cam with bolt and washer and a hardware package just below; (3) rotor; (4) more wire
Bottom Row L/R: (5) HT wires; (6) voltage regulator; (7) stator unit; (8) advance unit; (9) twin ignition coil

You also get an instruction booklet (not shown)

In addition, I have added to your kit items not supplied by the factory, but needed to successfully complete the installation:

regulator and custom mount optional PowerDynamo rotor puller pullers
(1) a custom mounting plate for the new voltage regulator , (2) the optional PowerDynamo rotor puller and (3) a puller to remover your old generator and magneto rotors.

Let us digress here for a short discussion about the magneto rotor and generator rotor/armature removal tools, referred to here as "pullers." In the far right photo above you will see pullers of different lengths displayed. The top shorter puller, which many of you may have in your tool kits, is suitable only for removing the generator rotor/armature, but is too short to remove the magneto rotor. For that task the bottom longer puller is required. Fortunately, the longer puller will remove both the generator rotor/armature and the magneto rotor. It is the longer puller capable of removing both the generator rotor/armature and the magneto rotor that I add to the kits I ship.

The center photo shows the optional PowerDynamo rotor puller. This puller is used to remove the new PowerDynamo rotor and will be required to set the initial ignition timing. It is a must have item, but does not come in the factory kit. I also add this required item to the kits I ship.

Preparing the motorcycle:

(1) Make sure your motorcycle rests securely, preferably on an elevated work bench, and that you have good access to the front of the engine. You will need to turn the front wheel from time to time for better access.

(2) Disconnect the battery ground wire (-) at the battery followed by the battery positive wire (+). You might as well remove the 6v battery from the bike now as you will be replacing with a 12v version.

(3) Follow the PowerDynamo factory installation precautions to drain your fuel tank into a safe container. Disconnect the connecting tube under the gas tank and and remove the fuel tank from the motorcycle and set it aside in a safe place.

(3) Remove the spark plugs, remove the inspection hole plug on the left side of the motorcycle just aft of the oil filler. Crank the engine by hand until the "F" appears in the inspection window. We'll refer to "F" mark later when installing the PowerDynamo rotor.

Removing the old 6v generator and magneto:

(Note: For the description below of the removal of your old generator and magneto I have liberally borrowed wording from from the Barrington Motor Works "BMW /2 Restoration and Service Manual." In my opinion, no /2 owner should be without this excellent reference.)

Check that you have disconnected the motorcycle battery and then unbolt and remove the front engine cover--you may need to tap the cover lightly to free it. Maneuvering the front cover off over the electrics and by the frame and front wheel can be a bit frustrating. On my R69S I usually disconnect the horn and steering damper to make more room. With the front engine cover removed you now have access to the bike's magneto (top) and the generator/voltage regulator (bottom).

Note: the color of your generator and magneto wires may not be the same as the colors on the machine in the photographs but the photos clearly show the wires attached to the generator and magneto. Just make note of any color difference between the bike wiring shown here and your bike. I just not sure how many different wiring harnesses are out there.

engine frontengine frontengine front

The left photo above shows the R69S crankshaft damper. On other /2 machines you will see only a bolt.
In the middle photo the damper is unbolted and being removed, revealing the generator assembly.
The right photo shows from bottom to top: the generator and above the engine centrifugal advance mechanism bolted to the camshaft nose
with the magneto body behind. Above the magneto body you get a peek at the coil (orange). We will remove these component one at a time.


R69S generatormagneto
(L) Generator (field assembly and rotor) (R) magneto and coil

Note: flag the wires [1] [2] [3] and [4] so that you can find them again after the motorcycle main wiring harness has been pulled out of the front engine compartment. We will later connect [1] and [4] into the PowerDynamo wiring harness, and will connect [2] and [3] together. We placed numbered tape on each wire as we removed it.

Disconnect the wires from the old generator, regulator and magneto. At the generator there should typically be:

Removing the old generator field assembly:

removing old generatorremoving old generatorremoving old generator

With the wires removed from the generator, use a 5mm Allen (hex) wrench to remove the two bolts retaining the generator field assembly to the engine casing. Then remove the field assembly. You might may to gently bump its side with a rubber hammer to disengage it. The generator on the R69S had a electronic voltage regulator and it was removed with the generator field assembly. You should also be able to do this if you have the old style mechanical voltage regulator.

removing old generatorremoving old generatorremoving old generator

Used the supplied puller to "pop off" the generator rotor/armature. If the rotor fails to pop off when the puller is tightened, a sharp rap to the puller head will usually free the rotor, but be prepared to catch it as it breaks free. Store your old generator, carefully wrapping the parts to avoid damage. One of the neat features of the PowerDynamo 112v conversion is that it's completely reversible and the motorcycle can be returned to its original 6v electrical system configuration.

Now on to the magneto:

removing the old magnetoremoving the old magnetoremoving the old magneto

Use a 10mm wrench to remove the 2 nuts (left and right side) which hold the magneto body to the engine block. Save the two nuts as they will be used to install the PowerDynamo ignition coil. Remove the magneto body (including the coil) from the engine gear cover. You may need to tap or wiggle the magneto body to free it.

removing the old magnetoremoving the old magneto25mm rotor

Thread the same puller bolt that you used to remove the generator rotor/armature into the magneto rotor and tighten gradually until the rotor pops off (yes, this one came off with an audible "pop"). If rotor does not come free, you may need to rap sharply on the end of the puller bolt to "shock" the rotor top engine coverfront of enginefree. Again, be ready to catch the magneto rotor when it breaks loose.

The factory instructions make a point of checking the diameter of the magneto rotor stub to confirm that it is 25mm. Some R60 and R69 machines have a 28mm rotor and require that the camshaft seal be replaced. This will not be a problem if your bike is an R50/3, R60/2, or an R69/2, as all of the machines have the 25mm diameter magneto sealing stubs. As you can see in the photo on the right above, the 1966 R69S magneto rotor checks out fine at 25mm.

Finally, we need to get the old engine wiring out of the way. Open the upper engine (breather) cover and and pull the motorcycle wiring harness back though the top of the case and stow it out of the way for the moment.

Good, we now have a "clean slate"--actually a bare engine gear case cover. In the photo on the left you can see the the nose of the engine crankshaft (bottom) and the nose of the camshaft (top). You next will be installing Powerdynamo components in both of these areas.