Motor-Head!

Mark is almost there with the CB750 – but he does try to do things on the cheap! It’s why we love ’im…

- Mark Haycock

The K2 engine was nearly ready to go, but there was just one last check and that was to the ignition system.

The contact breaker and auto advance unit are mounted at the end of the crankshaft under a chrome plated cover which I must admit had seen better days (Photo 1). This appears to be another example of how these bikes are knocked about during transporting from the USA, which is quite annoying as this is not an especially cheap part. This is what it looked like after being beaten out to greatly improve the appearance.

After taking off the points mounting plate, I checked the points and decided that they would best be replaced (Photo 2), and here I was faced with a choice: genuine Honda or pattern parts? To help you make your mind up, all I need to do is to tell you that the Japanese-made Daiichi pattern parts are available for less than a tenner for each set (the CB750 has a separate set for each pair of cylinders) but the genuine ones – which are still available – are £33 per set. So that is a difference of £46 for the pair and there seems to be no significant difference between the two types. So it is not too hard to choose – though later on in this series we will see that things are not quite as straightforward as they seem.

You should always check the capacitors, especially in this case considering they are now getting on for 50 years old and (in Photo 3) I am checking one with a multimeter which can read capacitance. I am getting the reading 244 picofarads which is usually expressed in automotive circles as 0.24 microfarads and this is correct for this application. The other was similar. Strictly speaking, the tests should include putting a high voltage across the terminals to check the dielectric but as I do not have a suitable instrument I had to assume they were okay.