Lester’s Norton Commando 850 Mk 3

Lester’s other bikes are fast, modern things. This is a machine for calmer, lazier days.

He’d bought it half restored: engine rebuild by Andover Norton, much of the chassis by the bloke who sold it to him. Which sounds fine, but Lester had discovered a lot of missing pieces, each of which had to be sourced and bought. He is now on first name terms with the spares bloke at Andover.

We discussed positive vs negative earth – he preferred negative. He also wondered what the best ignition system for a Commando is. Drawing on the opinion of my vastly more experienced mate Jim Hodges, I suggested Tri-Spark. (Jim is a very skilful engineer who has been building and modifying Brit twins his whole life.)

On the diagram I have kept as many wire colours as possible the same. The big difference is that earth is now black, rather than red. The Tri-Spark needs two 6V coils in series, rather than the 12V ones actually on the bike, but Lester will sort that out later. There’s also a temporary headlight ‘on’ switch. There was a brass contact missing in one of the switches, so until another one turns up at the right money his ‘on’ switch is between the coils.

The handlebar switches themselves were showing their age, so I cleaned them up with ultrasound and reassembled using silicone grease and new cables. It takes a while, but it sets them up for another decade or three.

We had hoped to fit the ignition, but in the end we had to admit defeat: the gearchange mechanism wasn’t finished yet, so I couldn’t yank the engine in and out of gear to turn the crank back and forth. So the bike may be back later.