Lucas N1 magneto
Posted: Mon Mar 18, 2019 9:52 am
Hello all.
My Model 18S starts easily from cold, even if it's been stood for several weeks. Starting when hot is a different matter, it keeps me fit though. Having read various articles it points to the magneto condenser but I wanted to investigate further.
I removed the armature and there are a pair of light grey condensers, I've not seen this configuration before, has anyone else? The armature winding looks newish, as though it has been reconditioned. I've had the bike a couple of years but don't know the history of the magneto.
Anyway, I cleaned it all up and put it back together. I then popped it in the lathe, supporting the body, and span it up. I tried to measure the speed of the engine with a tacho when kicking it over, not easy, but I reckon it was about 180rpm so I set the lathe speed to minimum, 250rpm. I popped a screw into the plug cap and positioned it about 3mm away from the magneto body, set up like this I could get a good spark. With the lathe running I heated the body of the magneto with a heat gun, after a while the spark became intermittent and finally stopped altogether. Leaving the lathe running without heat the sparks returned after a few of minutes.
So, I believe I've proven the starting difficulty when hot is down to magneto. Am I talking complete rubbish?
I've looked at the condensectomy but with my magneto having a pair of condensers with what looks like araldite holding the condensers and wires in place it looks too tricky to try to cut the wires without striping the armature and I don't a suitable bearing puller to do that anyway.
I guess the next step is to get the magneto tested by someone who actually knows what they are going. Can anyone recommend someone, I'm in the south-west, near Bath.
Thank you in advance,
Chris.
My Model 18S starts easily from cold, even if it's been stood for several weeks. Starting when hot is a different matter, it keeps me fit though. Having read various articles it points to the magneto condenser but I wanted to investigate further.
I removed the armature and there are a pair of light grey condensers, I've not seen this configuration before, has anyone else? The armature winding looks newish, as though it has been reconditioned. I've had the bike a couple of years but don't know the history of the magneto.
Anyway, I cleaned it all up and put it back together. I then popped it in the lathe, supporting the body, and span it up. I tried to measure the speed of the engine with a tacho when kicking it over, not easy, but I reckon it was about 180rpm so I set the lathe speed to minimum, 250rpm. I popped a screw into the plug cap and positioned it about 3mm away from the magneto body, set up like this I could get a good spark. With the lathe running I heated the body of the magneto with a heat gun, after a while the spark became intermittent and finally stopped altogether. Leaving the lathe running without heat the sparks returned after a few of minutes.
So, I believe I've proven the starting difficulty when hot is down to magneto. Am I talking complete rubbish?
I've looked at the condensectomy but with my magneto having a pair of condensers with what looks like araldite holding the condensers and wires in place it looks too tricky to try to cut the wires without striping the armature and I don't a suitable bearing puller to do that anyway.
I guess the next step is to get the magneto tested by someone who actually knows what they are going. Can anyone recommend someone, I'm in the south-west, near Bath.
Thank you in advance,
Chris.