Magdyno testing & refurb - any suggestions where? B31 1954

[iansoady]

I think a decent mag is far better than any battery and coil setup as the latter needs a good charging system as said. For mag repairs I've always used Tony Cooper in Halesowen who really knows his stuff but I'm not sure he's still working. Contact details below.

110, Olive Lane,
Halesowen,
West Midlands,
B62 8LT
Tel 0121 559 2405

[Derek996]

I do like the look of the Thorspark system (esp if it keeps the manual advance and retard but as Derek points out above you have to have an A1 dynamo and battery for longer runs - short runs it uses little juice so you could go total loss - at a push!

A couple of years ago I fitted a Thorspark ignition to a friends Panther 120. It uses the same magdyno as the B31/33. It was very easy to fit but needed a slot cutting in the bottom of the points cover for the wiring to exit and does depend on having a charged battery although Thorspark claim it will run for many hours on total loss electrics.
More info here : https://www.sussexmotorcycles.com/thorspark.html

[Dean Southall]

I have used Armoto near Chesterfield for several years and have been very happy. Not cheap but good quality.

[Steve.S]

I wonder if you might have more than one problem here?
Firstly, I've found that failure to pick up from idle is caused by a very weak mixture, often due to either the pilot by- pass jet in the jet block, or the pilot jet in the carburettor body being  blocked. You could check these with a can of WD40 with an extension tube fitted. It could also be due to a badly worn carburettor. Open the throttle slightly and see how much play there is in the slide.
The other thing I would do is remove the fuel pipe from the float bowl, and see what flow you have through the pipe with the filter fitted. It may be frustrated.
The next time you go out, take an HT Neon with you. Then, when it won't start, you will at least know whether or not you have a spark.
You could test the magneto yourself if you had Spark Gap Tester. If the spark jumps a 5/16"gap, that would indicate the magneto is producing 15,000 volts. You could also heat the magneto with a hot air gun to see if you still had a spark.
I think you said in a previous post, that if you held the tickler down, the engine keeps running? Perhaps your float is sticking up intermittently? If it's a Monobloc, you could try it with 2 cover gaskets. I believe you've already tried running without the fuel cap fitted?
Finally, when it won't start, remove the spark plug to see if you've flooded the engine.
Let us know how you get on.

[neil1964]

The OP has three threads along the same issues.
The points you make are excellent many were suggested in this earlier thread:
https://www.bsaownersclub.co.uk/bsaoc_forum/index.php?topic=18617.0

[paulm]

i have both Thornspark and good mags, the Mag is just as good if correctly wound, i use Tony Cooper for my Mags

[V500]

I would agree, though a correctly-wound mag is better in the long run. Mags have run billions of hours in cars, bikes and planes in perfect reliability, while Thorspark are newcomers and obviously liable to any design or electronic faults which may surface over time.