Happy Easter everyone!
I'm having some running problems with my B31. It starts and idles perfectly but stutters and won't accelerate when you add throttle. Initially, I thought it was an air leak in the carburettor. However, after rebuilding the carb with an Amal stay-up kit, it still doesn't perform as expected.
The B31 has a Thorspark electronic ignition kit with manual advance/retard and I'm wondering if the ignition might have wandered. I can't find any instructions for the Thorspark unit online so I'd appreciate any information anyone has.
Many thanks.
I phoned Thorspark directly when I was having issues with a unit on a bike I'd just bought. I spoke to the owner and he emailed the fitting instructions etc. Nice bloke, but I wouldn't consider buying a Thorspark kit for any other bike, I'd just get the mag rebuilt.
I have the fitting instructions for a magdyno system from Thorspark. Send me your email by DM and I'll forward it to you
Cheers
Pete
I can't see how it would be ignition, even if the advance / retard was out by 10 degrees.
If it cuts, as in no fuel, try lifting the needle a notch or two. Have you altered the air-cleaner.?
Thornspark only eliminates condensor problems, the mag can still be faulty
Quote from: paulm on Today at 11:49Thornspark only eliminates condensor problems, the mag can still be faulty
Hmm
My understanding that with Thorspark the ignition becomes coil/trigger with battery required.
The magneto is not used in the conventional sense, all you need is the magneto spindle to be true and spinning in its bearings. It links the magneto drive pinion in the timing case to the electronic trigger in the magneto end plate. Because the trigger replaces the points the trigger can be rotated to advanced or retarded positions by the ignition lever and basic timing is set by the user with pinion/mag taper as usual.
Given the symptoms it sounds more like fuel/carb settings.
Has the carb had a winter lay off with modern fuel drying out inside it?
If so you need to strip and clean thoroughly, drain and wrinse tank and full with fresh petrol.
2c 😉
BTW- what carb (concentrics are notorious for blocked needle jets that are a pain to clear properly