User Guide

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