1. GENERAL INFORMATION GRAND DINK 125/150 ENGINE LACKS POWER Inspection/Adjustment Symptom Probable Cause Start engine and accelerate lightly for Clogged air cleaner Restricted fuel flow observation Clogged fuel line between fuel Engine speed Engine speed does tank and carburetor increases not increase Clogged exhaust muffler sufficiently Faulty auto bystarter Check ignition timing Split carburetor vacuum piston (using a timing light) diaphragm Correct timing Incorrect timing Faulty CDI unit Faulty A.C. generator 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 Blown cylinder head gasket Flaws in cylinder head Check carburetor for Improper valve timing 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 Oil level too high Correct and not Incorrect or Oil level too low contaminated contaminated Oil not changed Remove cylinder head oil pipe bolt and inspect Valve train lubricated Valve train not Clogged oil pipe properly lubricated properly Faulty oil pump Insufficient coolant Check if engine overheats Faulty thermostat 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 Air in cooling system 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 1-19