My little brother once acquired and renovated a BSA C11 motorcycle(650cc, one cylinder, side valve, fired once every alternate lamppost). The original owner, an old boy whose riding days were far past him, threw in the riding gear for free; a Belstaff jacket, so stiff with lube oil and grease it felt like armour, lace-up gaitered boots, gauntlets. My brother drew the line at the po helmet (which was so ineffective as to be illegal anyway), but otherwise the ensemble and the "chug, chug, chug" exhaust note, caused many heads to turn when he took it to motorcycle events at Oliver's Mount near Scarborough and elsewhere.

He was forced to sell it when insurance rates rocketed. (This was around 1980, when large numbers of youthful riders were let loose on some very powerful 125cc machines, and were wrapping themselves around trees with increasing frequency. The insurance companies drove the young riders off the roads in advance of legislation, by making it almost impossible to obtain cover. Although my brother's machine would just about reach 65mph downhill with a following wind and the pillion passenger jumping off and pushing, the insurance people only saw the magic figure of 650cc and charged appropriately.)

When the first prospective buyer called in response to the newspaper advertisement, my brother was out and I was in the house (I was back from University on holiday.) The punter asked me to turn the engine over. I was confronted with a lever on the handlebars which manually advanced or retarded the ignition. Making a guess as to which way it went, I pushed it fully over and kick-started the bike. Seconds later I was on the floor, moaning. When the kick starter on a 650cc pot kicks back, you know all about it.

My father told me about a certain notorious British two-stroke vintage machine, the Matchless, which he once rode. When the ignition lever was pushed the wrong way, it was just possible for the engine to back-fire, and being a two stroke, continue running backwards. Unsuspecting riders would then put it in gear, let the clutch out; and hurtle backwards.