Ezgo EXPRESS L4 Technician's Repair And Service Manual page 101

Read all of Section B and this section before attempting any procedure. Pay particular attention to Notices, Cautions, Warnings and Dangers.
adjusted valves, spark plug wires which are in poor con-
dition or poor quality fuel could also contribute to the
problem.
Use care not to over-tighten the plug. Over-tightening can
cause damage to the aluminum cylinder head threads.
FOUR CYCLE ENGINE
Engine Specifications
Engine Model ................................................. FJ400-D
Type.................................. Four Cycle, Overhead Valve
Number Of Cylinders................................................... 1
Displacement.......................................................401 cc
Rated Horsepower ............................................... 13 hp
Spark Plug Type ..................................... NGK BPR2ES
Spark Plug Gap ...................028" - .031" (.70 - .80 mm)
Cooling ............................................. Forced Air Cooled
Oil Filter ......................... Cartridge Type Full Flow Filter
Oil Pump.......................... Positive Displacement Pump
Engine Description
The engine is an air cooled, 4-stroke, overhead valve,
single cylinder gasoline engine. It incorporates a pres-
sure fed lubrication positive displacement oil pump with
a cartridge type full flow oil filter and a counter rotating
balance shaft.
CYLINDER HEAD
Compression Measurement
Tool List
Ratchet ........................................................................ 1
Spark Plug Socket ....................................................... 1
Extension 6" ................................................................ 1
Compression Gauge & Adapter (20 kgf/cm
Before measuring compression, do the following:
• Be sure the battery is fully charged.
• Thoroughly warm up the engine so that engine oil
between the piston and cylinder wall will help seal
compression as it does during normal running.
• Stop the engine.
Disconnect the spark plug cap (3) and remove the spark
plug (4) keeping the engine throttle and the choke valve
fully open.
Attach the compression gauge (1) to the adapter (2) and
insert firmly into the plug hole.
Place the spark plug cap (3) on the removed spark plug
(4) and ground the spark plug to the engine.
To prevent possibility of personal injury or fire,
do not ground the spark plug in proximity to the
plug hole. Keep the plug as far away as possi-
ble from the plug hole. Fuel drawn into the cyl-
inder will be expelled through the spark plug
opening and could be ignited by the ignition
system or another source, resulting in a fire.
Using the starter motor, turn the engine over with the
throttle fully open until the compression gauge stops ris-
ing.
Cylinder Compression should be between 9 - 11 kgf/
2
cm (128-156 psi)
If the compression is higher than 9 kgf/cm
Qty.
piston rings, cylinder and valves are probably in good
condition.
If the compression is over 11 kgf/cm
the following:
2 .................
) 1
1. Carbon build-up on the piston crown and cylinder
head - clean off any carbon on the piston crown and
cylinder head
2. Cylinder head gasket - use only the proper gasket.
The use of a gasket of incorrect thickness will change
the compression.
3. Valve guides and piston rings - rapid carbon accumu-
lation in the combustion chamber may be caused by
worn valve guides and/or worn piston oil rings. This
may be indicated by white exhaust smoke.
Repair and Service Manual
3
4
Fig. 18 Compression Gauge
2
(156 psi), check
ENGINE
B
B
1
2
2
(128 psi) the
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