F...F...Frustration

One should never make assumptions, everyone know that. However, I’m going to cast caution to the wind and assume that everyone involved with old motorcycles will know the spark at the end of the sparkplug must occur at a precise point in the induction cycle of a petrol engine. The crankshaft turns, the piston(s) rises and falls and, in the case of a four-stroke, a cam or cams operate valves which allow a fresh charge of fuel/air in and the spent charge out while the two stroke has ports opened and closed by the piston. Again, the assumption everyone knows all of these elements have to combine their actions at the correct point in the cycle and this is known as ignition timing for the spark and induction timing for the fuel system.

Getting the mixture into an engine is relatively easy – a two-stroke