Magical mystery tour

I would love to be able to offer Brian Ling an answer to his query about piston rings ‘migrating’ into the lined up position (OBM 427) but all I can do is muddy the water.

In the Sixties I was a mechanic at North Anglian Autos in King’s Lynn. Despite the name we sold bikes, not cars. A mechanic from our Wisbech branch was visiting and he watched as I fitted a ring compressor to the piston of a four-stroke single in preparation for fitting the barrel.

Now, Wisbech was the fount of all motorcycle knowledge, or so we were led to believe. He pushed me aside, slipped off the compressor, spun all the rings for the gaps to line up and offered the barrel at an angle and lowered it into position. I asked about the gaps and he said that it was all tosh. I’m glad to say that in this instance he was right. The oil consumption was normal and the bike covered many trouble-free miles.

Another ‘mystery’ concerns my own ride to work bike, an Enfield

350 clipper, at around the same time.

The Lucas coil failed and I fitted a new one from the stores. Ten miles later on my dark journey home there was an almighty bang and I coasted to a stop. A chap allowed me to park in his garden and I walked home. Next day I collected the bike and I was astonished to see that the plastic top had blown out with such force that the aluminium crimping around the top had straightened out. A second new coil got me home and then that one blew up the next morning on the trip to work.

I got on the phone to a stroppy ‘Prince of Darkness’ and was quizzed about where I had fitted coils and was informed that it was all my fault for fitting the coils terminals up. My protests that I had never encountered a coil fitted terminal down was brushed aside – but I was asked not to fit a third coil from our stores but to return it to Lucas.

I borrowed a second-hand coil from a wrecked machine, fitted it terminals up and had no further trouble. To replace the two parts that had blown up and the one we’d returned, Lucas sent us one free coil! We asked for two more and for a report of its findings but got nothing.

One thought, it was impossible to ascertain the volume of oil in the coils as it was all over the rear of the bike. Any ideas out there?

Mystery three. I was asked by a local chap to go and have a look at his Enfield Flying Flea which had no spark. During my examination I found that if I turned the engine backwards it had a big fat blue spark. I reasoned that the flywheel magnets had reversed polarity, so I drilled them out and replaced them the other way around and off she went. My query is, why should the magnets reverse in a regular rideto-work machine? I was told it had only been unused for a few days.

Mystery four. This one was a Honda lawnmower. I was offered a very clean mower at a knock-down price because it had a starting problem. The seller demonstrated by pulling on the cord repeatedly but with no luck. He then took a four inch nail with the point cut off, inserted it in a hole in the top casing, gave it a smart whack with a hammer – one pull and it started! I made a silly low offer and I was the new owner. I used it for years like that and it never failed to start if it got a whack on what turned out to be the HT coil. I’m told that this 'excites' the coil. My question is, what is the science behind this?

Bill Woolnough, Swanton Morley, Norfolk