AJS & Matchless Owners Club

Hello again. After a couple of days of good fortune I'm now taking a step backwards again. The bike fired up nicely for a couple of days but now doesn't want to know. I am getting an intermittent spark from the plug connected by the Thorspark.

What I do know. The resistance across the coil tabs is 5.5 ohms. Coil tab to HT cap is 9K ohms. I have a good earth from both the battery and the coil using proper earth cables. If I hold the plug end and the handlebars and give her a kick I sit up and take notice but not necessarily on every kick. The resistance across the plug cap (black rubber one) is anywhere between 0.6 and 1.8 ohms, depending on how you wiggle the multimeter probes (funnily enough the one on the cub shows no resistance and no continuity). The plug is a brand new N5C. The coil and the HT cable came with the Thorspark.

Any comments would be helpful.

Can't help with the intermittent spark but I also had the same issue with a Thorspark unit. One day it'd fire and then the next nothing, sent it back for testing and was told all was ok so it must be my wiring. Not a chance that it was the wiring so I took it off and went back to magneto and all my troubles went away. I still have the Thorspark unit and it'll either go in the bin or onto the jumble stall.

I have never expérienced a Thorspark unit, but I agree with Rob : back to the mag could be a good thing. Mine was fully reconditionned last year by Brightsparks, and it runs very well. Fat blue sparks at amazing low crank speed.