Powerdynamo brings new ignition & light 
to your vintage motorcycle



Technical Help



In quite a few of our systems a twin outlet ignition coil is used. Those coils do have a few particularities which you should know
In  coils with one exit:

one end of the secondary coil is connected to the spark plug and the  other to ground.
  In our twin outlet coils:

both ends of the secondary go to spark plugs

typical resistance between both exits is 6.2kOhm

This leads to a few important conclusions:

You have to connect both plugs to make it work!
Ignition will only work correctly if both plug terminals are connected. You may not test one side by pulling the other plug! Each plug requires ground of the other side. If you want to test only one side, securely ground the other, by screwing a small woodscrew into the HT cable and clamp this screw to ground (cylinder) (see photo ).  Than the twin coil behaves as a single coil (see sketch above).

If the flow from ground via the plug, the coil to the other plug and its ground is broken, both plugs will not work - or get get some hefty fireworks around some spot near ground.

Please also see our information on "i get only spark on one side"
You may use a twin coil also for engines with only one spark plug
For this you just ground one exit. You screw in some HT cable and connect it to good ground (engine/chassis)(see photo ). 
Resistor sockets, high tension wires and spark plugs have to be good on both sides!
The ignition current has to pass both sides. If components there are bad, those negative values double, ignition gets weaker. If one side fails, both will fail.

Please do not get fooled by good optics of spark plug sockets, many a socket has a corroded resistor inside, even if never used. Check resistance with ohm meter, preferably on a hot socket (resistance increases in hot condition). Never use sockets with more than 5000 ohms, better 1000.
Most problems customers report, have been found to be due to bad high tension circuits (ht wires, sockets, sparkplugs). This is even more true with the twin outlet coils. (Small side remark: most of the remaining problems are due to bad earth connections.)
Last thing to mention, both exits always fire at the same time (something many original systems equally do). Different is only sense of polarisation, something that you might notice when using a stroboscopic light.

There can also be some amount of carbonisation at the spark plug getting the positive spark. This is however not a serious problem and, unfortunately, it can not be helped..
It is possible to replace the twin coil by 2 single coils if this is really needed for an application. (This is NOT possible with the sportssystems having an internal flywheel).