Sunday, 24 May 2020

A Sketch from the Past

Since there was a good going storm here yesterday I decided to tidy up my study. In the course of which I found a sketch I’d made many years ago.

Lots of washers!

This is the contact breakers on my first bike – Yamaha CS5E 200cc two stroke twin. So I would have made the sketch in 1975. 


Those of you younger than late middle age may not know what contact breakers are. And for that you should be thankful. Contact breakers were part of the ignition system. They switch the power to the ignition coil on and off as the engine turns. This causes the coil to produce a high voltage that provides the spark that ignites the fuel.

Contact breakers required maintenance. Wear in the fibre follower means that the ignition timing can go out and make the bike badly. In addition, because there is sometimes a spark as the point separate, the faces of the contact surfaces can become pitted. Replacement points should then be fitted. 


A contact breaker. The fibre follower is at the bottom and the points on the left

Back in the day points for Japanese bikes were expensive. Unlike cars bikes did not use distributors so there were a set of points for each cylinder. What I guess I was doing when I made the sketch was taking the breaker assembly apart to file the points smooth.


Points on a Suzuki GT750 - one set for each of three cylinders. Much fun adjusting these

By the late 1970’s points had been replaced with electronic ignition which requires no maintenance.

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