Technical Q and A for classic motorcycle maintenance and repair.
Editor’s note: If you’re having trouble with that old Suzuki, BSA or BMW, Keith Fellenstein is your guy. From motorcycle tuning tips to detailed motorcycle engine repair, he can draw from a wealth of experience to help guide you to success. Send questions to: Keith’s Garage, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as the subject.
Q: Where can I find the same colored wire on my 1974 Triumph Trident without buying a whole harness? I’m looking for small spools. Also, why do I have 6-volt coils with my Boyer ignition and a 12-volt battery? — Mike Stroobants, via email
A: You can find the individual wires you need to match your harness at British Wiring. They have complete harnesses and also the individual wires in a variety of color combinations, sold by the meter. The reason you have two 6-volt coils in your ignition is the Boyer is a wasted spark ignition; it fires both coils every time one of them needs a spark. One of the cylinders will be on the compression stroke and the other will be on the exhaust stroke. That means the coils have to be in series electrically, so two 6-volt coils present the same electrical load as one 12-volt coil would in a points-fired ignition. In a points-fired ignition, each coil is wired to a set of points and each coil is charged and discharged singly, so the electrical load flips back and forth between coils as the engine runs. Another way to do this would be with a single 12-volt coil with two spark outputs. MC