Part II Maintenance
7
①
. Remove the spark plug cap.
②
. Remove the spark plug with the spark plug socket
wrench.
③
. Visually inspect the spark plug insulator for damage. If
the insulator is damaged, replace it with a new one. If the
electrode has carbon deposits, clean it with a wire brush.
④
. Measure the spark plug clearance with feeler gauge.
The proper clearance shall be 0.70-0.80 mm; if adjustment
is required, tap (when the clearance is large) it or gently
pry up the electrode with a straight screwdriver (the gap is
too small).
⑤
. Check that the spark plug washer is in good condition.
⑥
. Install the spark plug, tighten it on the cylinder head
with a spark plug socket wrench, and install the spark plug
cap.
In order to prevent disorderly thread when installing the
spark plug, first screw in the spark plug with hand in the
direction indicated by the arrow (on the threaded hole of
the cylinder head), and then tighten it with the special
socket.
If a new spark plug is installed, an additional 1/2 turn shall
be tightened after pressing the washer.
If a used spark plug is reinstalled, an additional 1/8-1/4
turn shall be tightened after pressing the washer.
Spark plug torque value: 22 ± 2 N·m
2-5 Adjustment of valve clearance
There is a certain valve clearance between the tail end of the valve stem of the gasoline engine and its
transmission part to prevent the normal operation of the gasoline engine from being influenced by part
expansion and contraction. During work, too large valve clearance will lead to poor exhaust, which will not
only affect the dynamic performance of the gasoline engine but also increase noise (abnormal valve noise);
while, too small valve clearance will lead to loose valve closing, which will result in the failure of normal
operation of the gasoline engine and may result in the damage to the working surface of the parts of the
valve train.
Generally, the valve clearance of the gasoline engine must be checked and adjusted after 1 year or 300h
hours of use.
The valve clearance must be measured when the gasoline engine is cold.
Please note that there will be oil leakage when the cylinder head cover is disassembled.
Spark plug socket
Clearance
Measuring electrode
Wire brush
