Amal 376/67 carb

Stan Palmer · Post by **Stan Palmer** » Tue Mar 23, 2010 8:49 pm

I will be interested to see any replies on checking the magneto. I now have 5 as well as the one that's fitted. I need two for current projects, they all spark but after my experience with bike 1 I wouldn't use any of them without a full overhaul. Several don't feel as strong magnetically as the others, but hard to tell as two are N1, two are KF2 and the last is a racing type (single). End float is easy to check, that's about all I know. Safer to pay for the proper check I think.
Stan

1608 · Post by **1608** » Tue Mar 23, 2010 9:10 pm

I agree with Stan, get the Mag reccoditioned,I have had to have four recconed over the years and had many trouble free miles (ignition that is).Mags are difficult to check properly without the equipment and the know how, the condensor is burried internally and they can appear OK when testing with plug laid on engine but break down when plug is under compression etc etc. Reccon for piece of mind and discount ign probs when future fault finding.You can't repair a Mag at the roadside.

GSAX1 · Post by **GSAX1** » Tue Mar 23, 2010 10:12 pm

The condenser on Lucas mags have a 20 year or so lifespan. After that they either short out or open circuit. These faults mostly show up with a hot engine.

If the condenser has not been changed then I would strongly advise you to have it done. It is a specialist job, unless you are very familiar with electrics and the theory behind.

The way I test mags is to mount them in my lathe and let them run for some hours, until really hot. I have made a spark gap device, that let me adjust the gap "on the fly". A good mag should be able to spark at least 6 mm in open air, when hot, at low speed (2-300 rpm).

MichaelEdited by - GSAX1 on 23 Mar 2010 10:16:46 PM

gsneyd · Post by **gsneyd** » Wed Mar 24, 2010 1:09 pm

To give a rough check and confidence boost on the condition of the mag, connect a strobe torch in series (as is normal) and check that it fires the stobe every kick. Mine took 8 kicks to light the strobe (ie that is fire the spark plug) - and this was after a recon! The problem was that the points were yuk. Stoned and polished I got a a spark every time. Starting is improve but still fairly poor so need to go down the carb refurb route.

Graham