But it wasn’t straightforward.
First, I checked the points and surprisingly they looked brand new with no pitting on the contact faces. Another sign the Cyclemaster has not been used since refurb. I set the correct gap of 0.015″ to 0.018″ and still no spark. No loose wires and the rotor magnets seem well magnetised. So back to basics. Draw the circuit and check the resistance of each coil and lead and see if that shows the problem.
The resistance of each coil checked out OK… but the wiring didn’t.The HT lead was soldered to the LIGHTING coil. Oops, looks like the engine has been rebuild, but not by an electrician. Let’s hope their mechanical skills were better. So now I have a spark… but it’s weak and intermittent, so I figure the capacitor (or condenser as it was called) is weak – not surprising as they suffer with age and they weren’t that good when new.
Now being an environmentally friendly person who prefers to recycle and reuse, rather than replace (i.e. a skinflint), I decided to re-core the existing brass bodied part.
Farnell supplied the 0.1µF capacitor on the left, for a very reasonable 95p.It needs to be a polyester film capacitor, with a voltage of more than 75v. Go for one with a high maximum pulse rise time (V/µs) for long term reliability. Cut the end off the old capacitor and remove the internals but keep the cardboard liner to act as an extra insulator. It also makes the new capacitor (10.5mm OD) a nice slide fit in the brass body.
Solder a lead to one end of the new cap as shown. I used adhesive lined shrink sleeving over the soldered joint to insulate it and give mechanical support. Put some 24hr epoxy resin glue into the brass pot, insert the new capacitor and solder the end to the brass body, where it exits through the small hole in the end. (LH end in RH photo above). Don’t worry about polarity, as film capacitors aren’t polarised.
I made a small brass washer for the end where the wire exits and added more epoxy glue. The finished capacitor is on the right AND I’ve now got a consistent healthy spark – job done!
But I haven’t tried starting the Cyclemaster yet as I’m unsure whether to strip the motor.
If I don’t there’s a risk the clutch won’t split when installed in a bike and I’d have to strip it anyway. It’s probably also a good idea to fit new crank seals whilst it’s open, as the motor only has 0.8HP at best and I can’t afford to loose any. So I’ve convinced myself – full strip and check, coming next.