My B31 is intermittently cutting out and doesn't like re-starting.
It's very random and sometimes it runs OK.
I'm now in search of someone who can test my magneto / dynamo and refurb it if needed.
I'm based in Sheffield so local would be great but anywhere recommended would be great.
Thanks
Hi,
Try Priory Magnetos. Not very local but has a good reputation.
Dave.
Do you know about Thorspark electronic conversions for magnetos? -
https://www.sussexmotorcycles.com/thorspark.htm
They're relatively cheap and easy to fit. It keeps the manual advance/retard etc as it fits inside the existing magneto. My B31 has one fitted and it works a treat. Might be worth considering?
I had my B31 mag. overhauled by Priory Magnetos. Excellent service and a satisfied customer.
APl magnetoes Shaftesbury.
Quote from: KernowPete on 07 Apr, 2024, 07:07
Do you know about Thorspark electronic conversions for magnetos? -
https://www.sussexmotorcycles.com/thorspark.htm
They're relatively cheap and easy to fit. It keeps the manual advance/retard etc as it fits inside the existing magneto. My B31 has one fitted and it works a treat. Might be worth considering?
Just looked at the link (thank you)
Did you convert yours to 12v? And would it be a big job to convert?
Do you know which model of theirs, is fitted to yours?
Many thanks
Mine is 6v. It was fitted by a previous owner. Never confirmed if it is actually a thorspark but it's basically the same as I understand it
Here's a 6v one. Probably correct but you need to check it out -
https://www.sussexmotorcycles.com/thorsparksecureonlineshop/prod_955371-Lucas-MO1-Magdyno-bike-with-6-volt-electrics.html
Mine has a coil fitted under the top frame tube and the power connections run back to the battery with a switch and inline fuse holder. I believe you need a timing light to set it up but if you're happy with doing a bit of wiring it should be straight forwards.
Just reading some of the thorspark reviews and someone mentioned that sometimes their bike fires just from turning the ignition on. I've had the same thing on mine and something to be aware of is it might be more likely to kick back whilst turning over slowly to get past TDC. It's happened to me a couple of times before I learnt to leave the ignition off until I give it starting kick. The kick backs were very soft though so not too serious :)
I'm actually in the middle of rewiring my battery and ignition supply as it was badly grafted in to the original wiring resulting in a misfire when the lights were on. This was just down to poor connections. If you decide to go for one of these I'll happily send pictures of what I've done etc.
Quote from: Fraz on 07 Apr, 2024, 12:22
...And would it be a big job to convert?
I run my B32 at 12V. When I bought it had an E3HM 36W dynamo fitted which didn't work anyway and needed a rebuild but I managed to obtain a non-working E3LM which is a 60W model. I then rebuilt this with a new 12V armature and 12V field winding and of course new bearings and brushes. I fitted a DVR2 regulator into the old Voltage Control Unit and a 12V battery inside the existing Exide shell. Not cheap, probably cost the best part of £200 altogether but has the convenience of bulbs being easily obtained and less current through the wires, although I'm running LEDs throughout now.
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!
Have you cleaned the slip ring and made sure the HT carbon isn't stuck .
To the OP, before throwing money at it I'd suggest going back to basics and giving the bike a good check over. As the old saying goes, 80% of mag faults are down to the carb, etc etc.
That said, have you checked the spark when the bike is reluctant to start?
By the way this is mine -
https://youtu.be/ufXTNDL0ANs?si=qAF1onWPa7-qh4qH
Fell in love with the slow tick over ::)
If anyone knows this bike I'd love to hear from you!
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
Quote from: neil1964 on 08 Apr, 2024, 16:08
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 (https://www.sussexmotorcycles.com/thorspark.html)
I have used Armoto near Chesterfield for several years and have been very happy. Not cheap but good quality.
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.
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
i have both Thornspark and good mags, the Mag is just as good if correctly wound, i use Tony Cooper for my Mags
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.