Cylinder Head - HYOSUNG Aquila 250 Service Manual

◉ CYLINDER
● Apply BOND "1215" to the parting line of crankcase.
BOND "1215"
● Place the dowel pin ① and new gasket on the
crankcase.
CAUTION
Make sure to replace the gasket with a new one.
● Apply the engine oil to the conrod big end, piston and
the piston rings.
● Coat the cylinder wall with oil.
● Install the cylinder.
This cylinder is different from the front and rear.
With the cam chain groove of cylinder face the left side,
it is the front cylinder when the cam chain tension adjuster
be existed at the back.
◉ VALVE AND SPRING
● Insert the valve, with their stems coated with MOLY
PASTE.
Apply the oil to the lip of the stem seal.
MOLY PASTE
● The narrow pitch side of each spring face to the head
when the valve spring install. The pitch of inside
spring and outside spring is changed. The pitch of
spring is decreased from the upper side to the lower
side.
Valve spring compressor : 09916-14510
Valve spring compressor attachment

◉ CYLINDER HEAD

● Put in the valve spring and retainer, install the cotter
with compressed the spring by using the valve spring
compressor.
CAUTION
After installed the valve cotter, tap the valve stem
end by using the plastic hammer at 2~3 times for
assembly of the valve and cotter.
● Fit the cylinder head and tighten the stud bolts.
CAUTION
Pay caution to prevent the cam chain from drop-
ping into the crankcase.
Cylinder head bolt
: 21~25 N∙m(2.1~2.5 kg∙m)
: 09916H35C00
ENGINE 3-50
①
Broad pitch part
↓
↓
Head direction
↓
↓
Narrow pitch part