Kevin’s Yamaha XZ550

Why an XZ550? Why not?, asks Kevin. It’s a watercooled V-twin that was part of the mad scramble for supremacy between Honda and Yamaha in the early 1980s. Hardly anyone bought one, and it didn’t last very long. But in Kevin’s mind that makes it an attractive resto project.

Kevin managed to find a decent-looking wiring harness and meticulously cleaned all the connector pins in the connector blocks. But when he plugged it all in, very little happened. And what did happen was not very encouraging.

So he brought the bike along to the workshop to see if it needed a new loom. I love problems like this. You just find a wiring diagram, take your brain out, and set about testing the loom methodically. And having seen all the effort Kevin had already made, I was determined to save the loom.

The bike turned out to have 12 faults: the switchgear contacts were crusty so they needed stripping, cleaning and lubing. A couple of switchgear wires were pinched and broken (example in the photo). We also had a damaged regulator rectifier plug, two indicators that didn’t actually allow the bulb to make contact, loose-fitting bullet connectors (3.5mm rather than 3.9mm), a bad main earth, some warning lights in the wrong holes and a very old fuse box creating very high resistances. On top of that the flasher self-cancel unit didn’t do anything (I rewired it for a normal flasher unit). And the battery was on the way out. And the bike needed a new plug for the stator wires.

Kevin was pleased to see the lights and horn working, and a spark on cranking. With luck the XZ will run this spring, and we’ll see a picture of the finished thing.