Final Fettling.

Although I had set up the electronic ignition strictly by the instructions, I could only get her running with the stator plate at the extreme “advanced” position, so I thought that it was fairly likely that the timing would benefit from being properly set up with a strobe timing light. This is another first for me - it sounded very complex and technical. As with most things, once I thought it through carefully and logically it all started to make sense.

 The timing light works by taking a signal from the spark plug as it fires and lights the strobe light instantaneously at that point. So if you put some marks on the ignition rotor, you can use that to see whereabouts the position of the piston is as the spark ignites - i.e. “the timing”.

The manual told me that at low revs the spark needed to happen at 5 degrees before the piston was at Top Dead Centre (TDC) on the compression stroke. For higher engine speeds, this needed to be at 30 degrees before TDC. 

So I removed the spark plug and used a piece of dowelling down the spark plug hole to determine when the piston was at TDC and marked a line across the rotor and onto the alternator stator surrounding it.

Then I got the old school compasses and protractor out and made a disc that showed lines at 0, -5 and -30 degrees. I also cut a hexagon out of the centre to mount it on the rotor.

Then I transferred these marks onto the rotor and stator with a fine permanent marker.

With the engine running. I could aim the timing light at these marks and then adjust the position of the electronic ignition pickup until the -5 line lined up with the mark on the stator. It proved to be a mile out - it was +5 rather than -5. So the spark plug wasn’t sparking until the piston was well past TDC. This would mean that the power and efficiency would be compromised. As I turned it to the correct position, the revs rose very noticeably, confirming the more efficient running.

As a final check, at high revs I could confirm that the ignition was being advanced to 30 deg before TDC. 

With everything bolted back together again, I went out for another ride, this time venturing further afield around the local lanes, although I guess I was never more than about 5 miles from home (still a long push if she broke down!)

She was noticeably easier to start and ran more smoothly. I put about another 25 miles under her wheels and we’re up to 55 miles without any big issues now, which is really great.

Another job I did today was to fit a new fuel tap, which also has a reserve facility, so that gives me a bit more comfort as well till I get used to how far she’ll go on a tank!