Boyer Bransden Ignition

Posted: November 26, 2010 in British Bikes, classic bikes, Norton Commando, Triumph Bonneville, vintage bikes

Just to clear up some questions I thought I might put down a few notes about Boyer ignition kits.

The basic Boyer ignition is not a capacitive discharge system. It’s basically a points and coil system which is triggered by a Hall effect trigger instead of a set of points. Hall effect trigger you say?? Sounds scary; sort of like a sci fi armament device dunnit?

All it refers to is the fact that a magnet passing by a conductor (piece of wire or a coil of wire) will generate current flow. So that little bar that gets bolted to the camshaft has a magnet at each end that passes by two coils of wire (one for each cylinder) attached to the points plate. When the magnet passes a coil it tells the ignition coil (the ones under the tank) to fire. Since the points plate has a trigger coil for each cylinder you get a “waste spark” for each revolution.

Also note that the ignition coils are wired in series which further explains the waste spark. It’s the easiest way to retrofit the system to eliminate the points but it does give you an extra spark you don’t need. But it doesn’t hurt anything so no harm no foul.

When troubleshooting the system please note that the system goes “live” but will then shut off if it doesn’t sense the camshaft is turning. So when you put a test light on the coils it will light up and then go out after a few seconds.

Leave the test light hooked up and manually turn the engine over and the light will go back on … viola.

Also to check to see if the system is working, pull out a plug if you haven’t already and wave a small magnet past one of the trigger coils on the “points” plate and it should generate a spark at the plug.

I don’t know if this helps anyone but I hope it does. Email me any questions.


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