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8-3 INSUFFICIENT OUTPUT
8-4 OVERHEAT
Phenomenon Possible causes Remedy
1. Low
compression
1) Loosen spark plug Retighten or replace gasket
2) Cylinder head gasket leakage Retighten or replace gasket
3) Piston ring(s) seizure or wear Replace
4) Piston or cylinder wear Repair or replace
5) Incorrect valve and seat contact Repair or replace
6) Valve stem seizure Repair or replace
7) Improper valve clearance Adjust
2. Ignition system
malfunction
1) Spark plug faulty Replace
2) Ignition coil faulty Replace
3) Improper air gap between ignition coil and flywheel Adjust
4) Magneto demagnetization Replace
3. Fuel system
malfunction
1) Throttle body clogged Check and replace
2) Improper fuel pump operation Check and replace
3) Fuel strainer or fuel hose clogged Clean or replace
4) Air mixing into fuel lines
Check and adjust connecting portion
5) Improper gasoline or water infiltration Replace
6) Improper pulsation damper operation Replace
4. Low intake air
volume
1) Air cleaner clogged Clean or replace
2) Throttle valve faulty Repair or replace
Phenomenon Possible causes Remedy
Overheating
1)
Cooling air flow obstructed at inlet or cylinder baffle portion
Clean
2) Improper engine oil Replace
3) Lean air/fuel mixture
Check and replace throttle body,
and pulsation damper
4) Excessive back pressure of exhaust system Check, clean or replace
5) Over-load Change to rated load
6) Clogged oil cooler Check and clean or replace
7) Loosen or missing spark plug cap Check and connect properly
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