TROUBLESHOOTING9-5Excessive noise from engine—Failed air induction system Check the air induction system.Repair or replace faulty parts.Clogged vacuum hose Clean the vacuum hose.Cracks and damage in vacuumhose Replace the vacuum hose.Damaged carburetor joint Replace the carburetor joint.Loose carburetor joint Tighten the carburetor joint boltsto the specified torque.Clogged air filter element Clean or replace the air filter ele-ment.Symptom Possible cause ActionsNoise heard from around pistonWorn or damaged piston ring Replace the piston and pistonrings as a set.Worn or damaged piston Replace the piston and pistonrings as a set.Worn piston (piston pin hole) Replace the piston and piston pinas a set.Worn or damaged piston pin Replace the piston pin.Worn or damaged cylinder bore Replace the cylinder, piston, andpiston rings as a set.Carbon buildup in piston head andcombustion chamber Clean the piston head and com-bustion chamber.Noise heard from around crank-shaftWorn or damaged crankshaft jour-nal or crank pin Replace the crankshaft.Worn or damaged big end bearing Replace the big end bearing.Worn or damaged crankshaft jour-nal bearingReplace the crankshaft journalbearing.Worn or damaged balancer shaftjournal bearing Replace the balancer shaft journalbearing.Symptom Possible cause Actions