2003 Suzuki LT-Z400 Factory Service Manual, Page 276Get this manual
SERVICING INFORMATION
ELECTRICAL
Complaint No sparking or poor sparkingSymptom and possible causes 1Defective ignition coil2Defective spark plug3Defective generator4Defective CDI unit5Defective pickup coil1 Excessively rich airfuel mixture2Excessively high idling speed3Incorrect gasoline4Dirty air cleaner element5Incorrect spark plug (cold type)Remedy
ReplaceReplaceReplaceReplaceReplaceAdjust carburetorAdjust carburetorChangeClean or replaceChange to standard spark plugReplaceReplaceReplaceReplaceReplaceChange to cold type spark plugTurn-upTightenAdjust carburetorRepair, replace or connect properlyReplaceReplaceRepair or tightenReplaceReplaceReplace batteryReplaceRepair or replaceReplaceReplaceRecharge or replaceReplaceRepair or replaceReplaceReplaceReplaceReplaceReplaceConnect, tighten or repair
Spark plug is wet or quickly becomes fouled with carbon