I once had a BSA Fleetstar which had a mysterious misfire. I couldn’t sort it, despite all the usual checks. I took it to a mechanic who did loads of work on it, before he found that by chance when he touched the ignition key the misfire stopped. The issue was the ignition key/switch internals. A new ignition switch sorted it. Jump forward a decade - my B44 randomly blew fuses when I rode it. All things checked out ok, so I bought a new ignition switch. Problem sorted!
I would suggest, if you haven't already done it, Stripping and cleaning the kill switch and make sure everything is ok inside it. I had one start to disintegrate due to age and vibration gave similar symptoms, another straw for you to clutch at Paul!
Thanks - the owner took it home to see how it went, but soon after, it started jumping out of third gear again, so it may return sometime in the future.
Try closing the plug gap down to 0.015" and if it fixes the problem you are getting low electrical power to the ignition coil so needing to re-establish good earths and clean all the wiring harness connectors. The problem is usually caused by bad earth connections
I bet it's something to do with the electronic ignition. If it was my bike I'd refit the points at this stage. This is the sort of niggle that causes bikes to be put away and neglected instead of being ridden.
I am usually in favour of retaining the points, but the electrics and points ignition were in such a poor state it seemed like a good idea to start with a clean sheet, replacing the generator as well, as an all in package to cover the lot. The misfire does appear to be clearing bit by bit, so maybe loose carbon in the engine after a long lay up? I am not sure at present.
I am no expert so I hesitate to chime in,but, have you ran bike in darkness?. I had an SR500 years ago that acted up like this. I saw a spark from plug/HT lead one night. Excuse an amateur if I'm talkng rubbish :)
Wasn't expecting to see this one again but we all know you're not letting it go until it's right. That sounds like a lot of advance but I have no frame of reference. If it had still been on points I would have pointed the finger at the capacitor breaking down with a high back emf. Otherwise she sounds quite happy.
The suggestion of the ignition key seems quite feasible. How many hundreds and hundreds of connections and disconnections have been operated on this switch? From the 23 minutes of the video, the fist heated up! I've been tricked with a new candle pipe with a very high pre-resistor value. There was little energy for the candle.
There is no switch for the ignition any more, Glaico, except for a push button to stop the engine, with this new ignition system and I even disconnected the wire to that switch to rule it out. I think it might be loose carbon breaking up and interrupting the sparks.
@@paulhenshaw4514 Very violent tensions make the substances involved in the detonating mixture volatile and even super conductive. This excessive tension ends up complicating rather than solving the ignition. Frankly, I was very happy at the time of the magnets and did not know.
It is self generating and independent of the battery, ignition switch etc. There is no switch for the ignition any more, except for a push button to stop the engine, with this new ignition system and I even disconnected the wire to that switch to rule it out. I think it might be loose carbon breaking up and interrupting the sparks.
Of course it's been a 'might some time' since last I piloted a small displacement bike, but the acceleration of this one, now, seems commensurate with the advancement of RPM's. Especially after (almost) negating that pesky top-end misfire. One that can be used as a reminder to up-shift...a free 'rev-limiter' of sorts ! BTW, near your starting site, is this intersection: i.imgur.com/sZZ4e5h.png . A bit dodgy, it being 'blind' to the Left, what ? Have you ever been caught out by a rushing lorry/motorcar there ? Two objects not being able to occupy the same space, type of thing. Perhaps it's my military training, but I be always apprehensive, and highly cautious, about what (who) might be lurking around such corners. i.imgur.com/IXLn7w3.png
There is no problem there, Amelie, that is just a track in front of that house, for access to its grounds and also a right of way for a farmer, into one of his fields.
Thank you for today's ride. I know this has been frustrating for you. I just have an uneasy feeling about this particular electronic ignition.
Thanks Herman, it seems to be clearing bit by bit - maybe loose carbon after a long lay up flaking off the piston and interrupting sparks, who knows?
I once had a BSA Fleetstar which had a mysterious misfire. I couldn’t sort it, despite all the usual checks. I took it to a mechanic who did loads of work on it, before he found that by chance when he touched the ignition key the misfire stopped. The issue was the ignition key/switch internals. A new ignition switch sorted it. Jump forward a decade - my B44 randomly blew fuses when I rode it. All things checked out ok, so I bought a new ignition switch. Problem sorted!
I would suggest, if you haven't already done it, Stripping and cleaning the kill switch and make sure everything is ok inside it. I had one start to disintegrate due to age and vibration gave similar symptoms, another straw for you to clutch at Paul!
Thanks - the owner took it home to see how it went, but soon after, it started jumping out of third gear again, so it may return sometime in the future.
Try closing the plug gap down to 0.015" and if it fixes the problem you are getting low electrical power to the ignition coil so needing to re-establish good earths and clean all the wiring harness connectors. The problem is usually caused by bad earth connections
I bet it's something to do with the electronic ignition. If it was my bike I'd refit the points at this stage. This is the sort of niggle that causes bikes to be put away and neglected instead of being ridden.
I am usually in favour of retaining the points, but the electrics and points ignition were in such a poor state it seemed like a good idea to start with a clean sheet, replacing the generator as well, as an all in package to cover the lot. The misfire does appear to be clearing bit by bit, so maybe loose carbon in the engine after a long lay up? I am not sure at present.
@@paulhenshaw4514 🤞
I am no expert so I hesitate to chime in,but, have you ran bike in darkness?. I had an SR500 years ago that acted up like this. I saw a spark from plug/HT lead one night. Excuse an amateur if I'm talkng rubbish :)
Thanks for your suggestion, John!
Wasn't expecting to see this one again but we all know you're not letting it go until it's right. That sounds like a lot of advance but I have no frame of reference. If it had still been on points I would have pointed the finger at the capacitor breaking down with a high back emf. Otherwise she sounds quite happy.
I think spark duration with a CDI is brief and thus prone to misfire.
The suggestion of the ignition key seems quite feasible. How many hundreds and hundreds of connections and disconnections have been operated on this switch? From the 23 minutes of the video, the fist heated up! I've been tricked with a new candle pipe with a very high pre-resistor value. There was little energy for the candle.
There is no switch for the ignition any more, Glaico, except for a push button to stop the engine, with this new ignition system and I even disconnected the wire to that switch to rule it out. I think it might be loose carbon breaking up and interrupting the sparks.
@@paulhenshaw4514 Very violent tensions make the substances involved in the detonating mixture volatile and even super conductive. This excessive tension ends up complicating rather than solving the ignition. Frankly, I was very happy at the time of the magnets and did not know.
Hi, Have you tried earthing the electronic ignition straight back to the battery
It is self generating and independent of the battery, ignition switch etc. There is no switch for the ignition any more, except for a push button to stop the engine, with this new ignition system and I even disconnected the wire to that switch to rule it out. I think it might be loose carbon breaking up and interrupting the sparks.
Of course it's been a 'might some time' since last I piloted a small displacement bike, but the acceleration of this one, now, seems commensurate with the advancement of RPM's. Especially after (almost) negating that pesky top-end misfire. One that can be used as a reminder to up-shift...a free 'rev-limiter' of sorts !
BTW, near your starting site, is this intersection: i.imgur.com/sZZ4e5h.png .
A bit dodgy, it being 'blind' to the Left, what ? Have you ever been caught out by a rushing lorry/motorcar there ? Two objects not being able to occupy the same space, type of thing.
Perhaps it's my military training, but I be always apprehensive, and highly cautious, about what (who) might be lurking around such corners. i.imgur.com/IXLn7w3.png
There is no problem there, Amelie, that is just a track in front of that house, for access to its grounds and also a right of way for a farmer, into one of his fields.