1970-1979 Ski-Doo Snowmobiles Service Manual, Page 47Get this manual
CHAPTER THREE 3Turn on ignition and crank engine overA fat blue spark should be evident across spark plug electrodeWARNING
On machines equipped with CD! (capacitor discharge ignition), do not hold spark plug, wire, or connector or serious electricalshock may result
4If spark is good, check for one or more of the following possible malfunctions: aFouled or defective spark plugs bObstructed fuel filter or fuel line cDefective fuel pump dLeaking head gasket (see Compression Test) 5If spark is not good, check for one or more of the following: aBurned, pitted, or improperly gapped breaker points bWeak ignition coil or condenser cLoose electrical connections dDefective CD! componentshave CD! system checked by an authorized dealerEngine Difficult to Start