Generac Power Systems R100 Operator's Manual page 18

6. ABNORMAL NOISES WHEN ENGINE IS RUNNING
TROUBLE CAUSE
Piston, piston ring or cylinder is worn
Connection rod or piston pin and piston pin hole are worn Replace the worn part
Crankshaft main neck is worn
Piston ring is broken
Too much carbon deposit in combustion chamber
Too small electrode clearance of spark plug
Too much fuel supplied to engine
Improper fuel brand
Engine is overheated
Improper valve clearance
Flywheel is not connected with crankshaft tightly
®
GENERAC
18 R100 ENGINE
REMEDY
Replace the worn part
Replace bearing
Replace piston ring
Clear away carbon deposit
Adjust electrode clearance properly
Check relative parts such as carburetor
Replace fuel
Find the cause for overheating and eliminate it
Readjust valve clearance properly
Connect tightly