no spark

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
Locked
onthebuses
Posts: 27
Joined: Mon Nov 24, 2014 9:37 pm
Location: ESSEX UK

no spark

Post by onthebuses »

Hi I've a 1950 g80 went out on it yesterday morning started ok run ok did about 10 miles parked up 2 hours later tried to start no joy ...... No spark whatsoever magneto rewind 12 months ago any suggestions please Thanks Gary
Andy51
Member
Posts: 741
Joined: Thu Mar 31, 2005 1:00 am
Location: BERKS UK

Re: no spark

Post by Andy51 »

Hi Gary, never had this happen with a magneto, but many years ago I was returning home on leave in my VW Beetle. The car was running perfectly until I stopped for a quick legstretch, luckily near home, and the wretched thing would not restart. My father came out to tow me back and pronounced the capacitor U/S. New capacitor and it ran beautifully. If the capacitor does go, the engine will often continue running until you try to re-start it. Unfortunately replacing the capacitor in a magneto is a tricky job - best of luck if this is your problem. Andy
G15 Roy
Member
Posts: 3546
Joined: Sun Jan 01, 1995 12:00 am
Location: ESSEX UK

Re: no spark

Post by G15 Roy »

onthebuses wrote:Hi I've a 1950 g80 went out on it yesterday morning started ok run ok did about 10 miles parked up 2 hours later tried to start no joy ...... No spark whatsoever magneto rewind 12 months ago any suggestions please Thanks Gary
Where was the armature rewound.
Roy
User avatar
Rob Harknett
Member
Posts: 11236
Joined: Mon Jan 01, 1990 12:00 am
Location: ESSEX UK

Re: no spark

Post by Rob Harknett »

Assume you have checked, plug lead and connections including brush has not got stuck. So remove the lead holder on the mag. to check the brush fits OK. Also points etc. have not worked loose. If capacitor is faulty, quite often the bike will restart when cold, then start to miss etc. and cut out when hot.
It could be mag winding failure.
ELPS
Posts: 39
Joined: Wed Jan 04, 2017 5:11 am
Location: WESTERN AUSTRALIA AUSTRALIA

Re: no spark

Post by ELPS »

I was given a spare mag when I got my G80. It had no spark. Eventually tracked it down to the carbon brush that sits under the N1 magneto tag. Was gummed up with crud. Cleaned it up and now have a good spare magneto.
Dave T_LAPSED
Posts: 157
Joined: Tue Mar 29, 2016 7:19 pm
Location: CALVADOS FRANCE

Re: no spark

Post by Dave T_LAPSED »

Hi, when you had the mag rewound you, of course, had a new condensor fitted, yes? Is it internal or a modern Brightspark type? If it's modern, replace it, it's simple , fitted under the points. If it's internal get it changed to the modern type. Your symptoms are similar to mine on my previous G80 1954 and it was the condensor at fault, Brightspark fixed it ! Condensors are dear little chaps, they can last for years or pack up in weeks. I would strongly suspect the condensor.
Locked