Honda CB160 Shop Manual page 22

18
Fig. 3. 33 Valve
Fig. 3. 34 Removing valve
Fig. 3. 35 Oiling the valve stem ·
Fig. 3. 36 Dressing valve seat
3. ENGINE
E. Description of valve
The valve performs the important role of air
tightness in the cylinder, of intake and exhaust for
compression and combustion, and extensively influences
the engine output.
At the exhaust valve, the camber is small, for ob-
taining better heat radiation and the clearance between
the stem and cylinder is made large. At the inlet
valve,
it
is large for increasing the intake efficiency
and the clearance between the stem and the cylinder
is made small for satisfying various conditions con-
cerning valve.
A double spring system is employed for the valve.
(Refer to Fig. 3. 33)
I.
Disassembly
1 • Remove the cylinder head according to Section
3. 2.1.
2. Depress the valve lifter spring and remove the
two valve cotter pins with long nose pliers or
tweezers, the retainer valve spring from the head
cover, and the valve from the combustion chamber.
(Refer to Fig. 3. 34)
II.
Installation
1.
Before the valve is assembled, the valve contact
surface should be inspected for wear, pitting, or
carbon. After cleaning, oil the valve stem, and
the valve should be inserted from the combution,
chamber side. (Refer to Fig. 3. 35)
2. The valve spring outer and inner retainers should
be fitted from the cap hole of the tappet adju•sting,
hole and be compressed by using the valve lifter.
Secure with the valve cotter pin.
Ill.
Valve seating
1.
Dressing of a valve seat is made by using three
cutters {such as a 90° plane cutter, INT AKE and
EXHAUST plane cutter, and INT AKE and EXHAUST
interior surface cutter.
2. The position of a seat is determined by the
INT AKE and EXHAUST plane cutter and the width
of a contact surface is determined by using an,
INT AKE and EXHAUST interior surface cutter.
3. When a seat surface is excessively burned, dress-
sing should be performed by using a 90° cutter so
that the seat surface becomes even. (Refer to
Fig. 3. 36)