Vintage BMW Motorcycle Owners

I’m racking my brain trying to figure out the issues I am having with this mzb power dynamo system. The charging system is working exceptionally....however I am having ignition issues.

The two issues I am having
- a stumble between idle and aprox 3k rpm. The engine will hesitate and surge a bit. After that the engine smooths out.

-at full throttle I have a loss of power power (top speed is down to 70-75mph)

I have tried two different sets of switch positions (as recommended by Joel rapose and Vape).

Timing light verification of the F mark dead center at full advance.

Joel was nice enough to send a spare black box to swap out....unfortunately with no improvement.

I’m a bit stumped.

Before installing this system neither of these problems existed with stock magneto ignition.

I would check the coil resistance as per the instructions on the website here: https://www.powerdynamo.biz/eng/info/2exits.htm

Also check resistance on your plug wires, caps and the plugs themselves. Check each individually and then as a total unit. You should be running 1k ohms caps and non-resistor plugs so the total resistance should be 1k ohms from coil to plug electrode. its not hard to measure and make sure you go to the center electrode of the plug.

Your advance seems to be right on which means it would not be your black box, Which you already tried. Also the dip switches only control the advance and other static settings. As you accelerate the pressure in your cylinders change drastically which is why I would look towards the spark side which would be wires, caps, plugs and coil. All dynamic.

If it were me I would put new wires, caps and plugs in and test it, but only after checking the coil resistance.

I did have a bad Powerdynamo coil once (it is rare) and the resistance went way up when hot. But that is not what is happening here so I would save that test for last. It’s a simple system and basically the same as the original /2 design, although upgraded.

Let us know how it goes.

sorry for the late response but I just want to thank you for your advice. I replaced the stock 0k ohm caps with a set of 1k ohm Beru plug caps and my problems disappeared. I'm still a bit baffled as to why the instructions state you can run 0-2k ohm caps. I just figured they would be fine since the instructions said they would be. Regardless the issues are fixed due to that little change in plug caps. Thank You!

A small amount of resistance for a coil forces the coil to “back up” and creates a better spark. Even with this I would think that the 0ohm caps might have had a problem as it should work with those. Either way it’s good to know it helped.

Hello:
I did not start a new thread as my question is related. Presently I am in the process of installing a Powerdynamo 12 V system on my R27. All is going well yet I am confused on one issue: connecting the output from the new voltage regulator to the bike's original electrical system. It seems like the regulator output would attach to both the red wires at the original regulator, but I am not sure how the ignition switch will then function properly, and don't want to get this wrong and ruin the components. Do any of you have experience with this installation? Thanks in advance.
Kevin

Kevin,

I have one on my R27 and it works GREAT! I love it. Lots more power than the original, seriously.

I am looking at the diagram at: https://www.powerdynamo.biz/wiredias/91ik.pdf and figure that is what you are referring to.

1) The wire that is marked "Existing electrical system" is exactly that. Look at the diagram, + comes off the battery and to pole #51 on the ignition switch as it does today. There is no change there!

2) What is confusing you is the charge control light. The way it is wired from the factory is that the positive pole goes to the common for both lights and ground activates the light. Hence, if you want the light simply hook the output of regulator #6 to the non-common pole fo the charge control light. Easy. gn/rt will be providing ground when the system is not charging. You can reuse the existing wire for this and not run a new one.

2a) I do NOT run the charge control light and have hijacked that red light to use as a positive blinker light. I always forget my blinker on!

3) If you really look at it there is only 1 new wire (and possibly not even that one) that needs to go to the headlight bucket. That is bl/ws for the kill switch. On a stock R27 you cut power to the coil to stop it, but since this is a magneto unit you need to ground the mag to stop the engine. Hence a new wire.

It is really a 1 wire system unless you want the charge light and then you need to find that one and splice into it.

The "existing electric system" coming off pole 15 is already there.

James

Last thing on the R27. I have two, one with Vape and one without.

The Vape unit runs so much better but starting is the only issue. It does kick back more, and it can hurt your foot/leg if you are not careful. You need to get your starting procedure right in order to minimize the kick back. Once running its a joy,

My other R27 has very little if any kick back and starts easier. Its not as powerful, smooth or fun to ride though!

Just get your starting procedure down right.

James

James: Thanks for your quick and thorough reply!

I had the powerdynamo on my R50 and decided to put in on the R27 for the 12 V and overall cost( less than replacing an armature, regulator and centrifugal advance unit.)

From your answer it appears that all I need to do is attach the two red wires at the existing, stock voltage regulator to each other to give continuity and then attach the red #5 off the new regulator to the positive battery terminal.

I think the charge control light will function if I attach the green/red #6 off the new regulator to the blue wire at the old regulator that goes to the headlight bucket and charge light.

So of course more questions:

Will the existing ignition switch still function to kill the engine without requiring some creative wiring of the bl/ws wire from the advance unit?

I am mocking up the installation before making it permanent, but thinking of of putting the coil in the stock location above the horn, and the regulator and advance in the battery compartment, possibly in one of the "dummy" battery cases that Vape sells on their website. How did you do yours?
Thanks again,
Kevin

James,
Can you please relate your starting procedure. I'd like to eliminate the kick back I'm having on my R26 with the VAPE PowerDynamo.
Jack

Wurzburg,

This is what I do with my R27 and it works great!

Cold start - Turn on fuel tap and wait at least 30 seconds. Tickle carb for a 3 count. Ignition off and half throttle give it two good kicks. Ignition on and crack the throttle and it almost always starts 1st kick.

Shut down - I always turn the fuel tap off before I kill the motor. I always wait at least 15 seconds after I shut the fuel off to kill the ignition. My hope is that I am burning the fuel in the fuel line while leaving some in the bowl is fine. This stops fuel from leaking into the motor and on the gearbox. When I shut it down for the day I let the motor run until it dies which drains the bowl as much as possible.

Warm start - Turn on fuel tap. Do not wait 30 seconds. I give it a quick tickle, maybe 1 second if that. Ignition on, crack the throttle and 1 good kick.

I would say mine starts almost always with a single kick when I get it right. Your motorcycle will like something different than mine so you need to find your right procedure.

Hope this helps.