1. GENERAL INFORMATION SUPER8 125 ENGINE LACKS POWER Inspection/Adjustment Symptom Probable Cause Start engine and accelerate lightly for observation Clogged air cleaner Poor quality fuel (Restricted) Clogged fuel tank cap breather hole Engine speed Engine speed does not Clogged exhaust muffler increases increase sufficiently Faulty auto bystarter Split carburetor vacuum piston Check ignition timing diaphragm using a timing light Faulty auto fuel valve Faulty CDI unit Correct timing Incorrect timing Faulty pulser coil Check valve clearance Improper valve clearance Correct Incorrect adjustment Worn valve seat (valve stem too protruding Test cylinder compression Improper valve and seat contact Normal Abnormal Worn cylinder and piston rings compression compression Leaking cylinder head gasket Improper valve timing Check carburetor for clogging Not clogged Clogged Clogged carburetor jets Remove spark plug and inspect Plug not fouled or Plug fouled or Fouled spark plug discolored discolored Incorrect heat range plug Remove oil dipstick and check oil level and condition Incorrect or Oil level too high Correct and not Oil level too low contaminated contaminated Oil not changed Remove cylinder head oil pipe bolt and inspect Valve train not Clogged oil pipe Valve train lubricated properly lubricated properly Faulty oil pump Check if engine overheats Worn cylinder and piston rings Mixture too lean Engine does not Engine overheats Poor quality fuel overheats Excessive carbon buildup in combustion chamber Ignition timing too early Rapidly accelerate or run at high speed Excessive carbon build-up in combustion chamber Engine does not knock Engine knocks Poor quality fuel Clutch slipping Mixture too lean Ignition timing too early 1-22