Suzuki LT-A400, Service Manual

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1D-28 Engine Mechanical:
Valve Seat Repair
B827H11406027
The valve seats (1) for both the intake and exhaust
valves are machined to three different angles. The seat
contact surface is cut at 45
°
.
CAUTION
!
• The valve seat contact area must be
inspected after each cut.
• Do not use lapping compound after the
final cut is made. The finished valve seat
should have a velvety smooth finish but
not a highly polished or shiny finish. This
will provide a soft surface for the final
seating of the valve which will occur
during the first few seconds of engine
operation.
NOTE
After servicing the valve seats, be sure to
check the valve clearance after the cylinder
head has been reinstalled. Refer to “Valve
Clearance Inspection and Adjustment in
Section 0B (Page 0B-4)”.
Camshaft Inspection
B827H11406018
The camshaft should be checked for wear and also for
runout of cams and journals if the engine has been
noted to produce abnormal noise if the engine has been
noted to produce abnormal noise or vibration or to lack
output power. Any of these malconditions could be
caused by a worn camshaft.
Camshaft Cam Wear
Worn-down cams are often the cause of mistimed valve
operation resulting in reduced output power. The limit of
cam wear is specified for both intake and exhaust cam in
terms of cam height “H”, which is to be measured with a
micrometer. Replace camshaft if found worn down to the
limit.
Special tool
: 09900–20202 (Micrometer (1/100 mm, 25 – 50
mm))
Cam height “H”
Service limit (IN.): 32.830 mm (1.2925 in)
Service limit (EX.): 32.830 mm (1.2925 in)
Camshaft Journal Wear
Determine whether each journal is worn down to the limit
or not by measuring camshaft journal oil clearance with
the camshaft installed. Use plastigauge to read the
clearance, which is specified as follows.
Special tool
: 09900–22302 (Plastigauge (0.051 – 0.152 mm))
Camshaft journal oil clearance
Service limit: 0.150 mm (0.0059 in)
Intake Exhaust
Seat angle 15
°
/45
° ←
Seat width
0.9 – 1.1 mm
(0.035 – 0.043 in)
←
Valve
diameter
30.6 mm
(1.20 in)
27.0 mm
(1.06 in)
Valve guide
I.D.
5.000 – 5.012 mm
(0.1969 – 0.1973 in)
←
1
45°
15°
I827H1140074-01
I827H1140075-01
“H”
I827H1140076-01