AJS & Matchless Owners Club

HI Guys I need some help please if anyone can advise, at the moment on my above motorcycle I am having a problem with no spark at the spark plug
I have lost the spark. The spark was there but whilst taking the back plate off I disconnected the points to replace them with new ones something has gone wrong I may have got the sequence wrong of putting the Condenser terminal and live wire from the stator. I have noticed that when I present and offer my back plate up to the cam when it touches the side of the timing control area it sparks and tracks out. It also tracks out at the spark plug when I have it resting on top of the rocker box, this is with out kicking it over to test for a spark when setting the timing, is this abnormal for it to happen.

Sounds like something is shorted. Are the points open?

HI Thank you for your reply Points at TDC are closed when I take the Timing spoke down to 1/2 inch they open. IT is whilst I am putting the whole back plate on to fasten up they start arcing and this is when it arcs through to the spark plug which is out of the spark plughole resting on top of the rocker cover.

Well as its an issue that has developed since you started playing with it then there is only a few things to look at.
Have you got it wired up the right way around?
Rotate the engine until the points close, using a screwdriver open the points, what happens?

As the moon is in a Waxing Crescent you might be lucky and Spridder might chime in, but don't expect sensible answers out of him if the moon is in the Waxing Gibbons stage.

Do you have the ignition turned off when replacing the back plate?

HI Guys good morning to you jackstringer ok I will go in my garage and get on that one , Hi Duncan ignition is on whilst replacing the back plate.

Mmmm...coil ignition too modern for me but I just wondered why you would have the system Iive (ignition on) whilst replacing the points? OK so I blew a fuse after forgetting to remove it whilst changing a battery recently but maybe that is not a risk with the ignition circuit.

Grinne wrote: ↑Tue Jul 25, 2023 8:25 am HI Guys good morning to you jackstringer ok I will go in my garage and get on that one , Hi Duncan ignition is on whilst replacing the back plate.

If the ignition is on the current will be flowing to the points and as you touch the engine housing it will arc causing the spark plug to fire, try turning the ignition off then replace the back plate, check you have a fuse from the battery before turning on in case you have a wiring anomaly.

HI Duncan thanks for that I Have tried with the ignition off it does not arch out, then when I offer the High Tension Lead with sparkplug Connected over the plug hole to test for spark I do not get any thing. I have noticed that when I go to turn the Ignition OFF I get a little trickle of spark through the sparkplug as though its Back tracking out.

Coil ignition is a bit too modern for me too, plus I don't see why you would have the ignition turned on when refitting the back plate.

The plug will spark only when the 6v supply to the coil is interrupted, either by design (i.e. by the c/b points opening) or by the 6v ignition circuit being unintentionally shorted out.
As has been said, you have probably fitted the connections to the new c/b points assembly incorrectly.