If it’s going to go wrong, it’s odds-on that it’ll be the electrics at fault–that vital motorcycle system that most riders neglect until it all goes south. Some repairs can be handled at the roadside. But when the magneto sparks finally stop flying, it’ll be someone like Stuart Towner who gets you back on track.
Stuart, who started out as a Fleet Street printer working with another kind of hot metal, has been repairing magnetos and dynamos since around 1992.
‘It was my late father’s business,’ he explains. ‘But my father did it mostly as a hobby, not as a full time occupation. Following my umpteenth redundancy, I realised that he’d been secretly preparing me over the years to pick up where he left off, and that’s exactly what I did.’
All the necessary equipment was lying in wait. The hand tools. The multimeters. The ancient, wheezy electrical device for checking coils. The old Champion spark plug tester. The little gadget that excites the armature and looks for unwanted earths. The numerous boxes of magneto and dynamo bits. And, most importantly, the raw know-how.
Working from his Chessington, Surrey home, 63-year old Stuart rebuilds magnetos for any bike going back to the Ark. But don’t be shy. He’ll sort out your tractor, your old Austin Seven, your stationary engine or what-have-you. All popular makes of dynamo catered for too.
Rudge and Vincent Man
Stuart is also an active Rudge and Vincent man with plenty of racing miles beneath his wheels, both in the UK and way down under. He regularly rides and parades his large collection of speedway bikes and other classic bikes, and is content that his life is largely "going around in circles". Meanwhile, he’s the editor of “The Radial”, the Rudge enthusiast magazine.
So how do you find the time, Stuart?
‘The time finds me,’ he explains, wryly.
His workshop is a small grotto of parts, new and ancient. A halogen heater keeps out the February chill, while a transistor radio warms away the February blues. He works deftly and methodically, a backwater electrical engineer confident in his skills. And without guys like him, the classic bike world would be a much less mobile place.
Magneto rebuilds cost somewhere between £160 and £180 on average (two year guarantee). Dynamo rebuilds are £75 plus parts (one year guarantee). Turnaround is anything from a couple of days to three months, depending on your urgency—and depending on how much work Stuart has taken on. He can usually accommodate people in desperate need of help, and biases his time towards the racing community who usually need help yesterday.
"I am winding down a little these days," says Stuart. "But I'm not done yet. I never advertise. I get work almost exclusively through word of mouth."
Stuart can sell you a magneto too. Typically, prices for an ordinary road-going mag for, say, a British single will cost around a couple of hundred quid. That's for a completely overhauled magneto with a two-year guarantee on the windings.
For a racing mag, you're looking at around £350. These prices are accurate as of May 2011.
Magneto tips and hints
"It's impossible to properly test a mag without the right equipment," says Stuart. "But there are certain indications when things are going wrong. Basically, if it starts okay from cold, but gives you problems when hot, that could be a sign of the magneto breaking down, or perhaps a failing condenser.
"But of course, there could be other factors, such as a carburation problem. So you'll need to check that first. With Lucas mags, I don't even bother to check the condenser. I just change them as a matter or course. Lucas mags, remember, are at least around sixty years old now, and there are still some around that have never been looked at—and they were never as good as BTH mags (British Thomson-Houston).
"Another good indicator of serious problems is sparking around the contact breaker. There should, of course, be a faint spark there between the points. That's normal enough. But anything more than that is invariably an indicator that the mag needs looking at. I've seen some in such poor condition that the contact breaker was like a Catherine Wheel.
"Bosch mags are also pretty good. But all mags have a certain life and will need attention. But once serviced, they're generally reliable and will give years of operation without problems. Just make sure that you don't let petrol drip from the carburettor onto the mag. That will eventually dissolve the shellac, and then the mag will break down.
"Another important point to remember is to never have a spark plug gap of more than around 15 thou gap. And don't run suppressed spark plug caps. That just makes mags work harder due to the extra resistance."
Stuart's telephone number and email address are to the left of this feature. Don't use the email button at the top of this page which will take you to Sump. You can often find Stuart at Kempton Park autojumble which is close to his home. He'll be out there trawling for spares and complete mags.
If you want to send a mag to Stuart, just use the Royal Mail or a courier, or you can arrange to deliver by hand if it's more convenient. But if you post it, remember to get it insured (whatever that's worth these days).
Take note that Stuart doesn't handle other electrical repairs. It's magnetos and dynamos only.