Refused to start after 10 mile run

[willowbedone]

The sun was shining So it's time for IST ride on the g12 .started IST kick ran fine But when I stopped it for a few minutes would not even think about starting .I checked the fuel in the float bowl ( ok ) Removed the plugs could see a spark so check points After a while away it went Thirty miles then home stopped it Yes you guessed would not start again Spark or fuel .Any thoughts would be welcomed
Thanks Ian

[ajscomboman]

Classic sign of a magneto issue manifesting. Cold it'll be fine when warm it's a bugger. Unlikely to be fuel related as it ran once fired up.

[Mollbhan]

Exactly what my G12 used to do, magneto problem, toss up between a magneto overhaul or a thorspark, I chose the thorspark and never regretted it.

[MalcW]

Exactly what my G12 used to do, magneto problem, toss up between a magneto overhaul or a thorspark, I chose the thorspark and never regretted it.

I had the same symptoms and had my magneto rebuilt (by Tony Cooper). All good since.

[spookefoote1956]

Thorspark wins for me too.

[willowbedone]

Thanks for all replies Does thorspark work ok with a dynamo

[Groily]

Ought to be OK as the current draw is very low, probably the lowest of the genre. A battery should last well in daylight or with LEDs, even if the dynamo misbehaved.
Just have to find a suitable spot to place for the double-ended HT coil (and decide whether to retain 'let's pretend' HT pick ups and cables off the mag).

[56G80S]

Tony Cooper rebuilt my SR1. All good. It had worked perfectly from when I got the Matchless (mid 1970's) until post 2000. On that basis, when it fails, I won't care.

Johnny B

[spookefoote1956]

Thanks for all replies Does thorspark work ok with a dynamo

Tip top. Very minimal power draw. I went with it due to finances.

[mdt-son]

The culprit is likely cracked insulation on the magnet's anchor windings.
A good magneto is always to be preferred as it will take you home irrespective of battery / dynamo / alternator problems. It also provides an increasing powerful spark with revs. A refurb gets my vote. The magneto will outlast you.

- Knut