Two stroke engines are notorious for eating spark plugs - this is largely due to the oil that they burn making a deposit on the electrodes. So, a plug that is sparking isn't neccesarily a good one as it may fail under compression pressure. So, to check for spark 1) make sure the side of the plug is touching the metal of the engine (very important), pull the starter cord. 2) have a look at the cut out switch, disconnect the wires if you can, try again. 3) Check the gap between the flywheel and the ignition coil - should be .25mm. If all else fails, and all electrical connections are sound, you'll need a new ignition coil (failures are rare).
John, December 2007
