
Subsection 08 (TOP END)
VALVE STEM DIAMETER
EXHAUST VALVE
NEW
4.956 mm to 4.970 mm
(.1951 in to .1957 in)
570
engine
SERVICE
LIMIT
4.930 mm (.1941 in)
NEW
5.461 mm to 5.476 mm
(.215 in to .2156 in)
850 and
1000R
engines
SERVICE
LIMIT
5.440 mm (.2142 in)
INTAKE VALVE
NEW
4.966 mm to 4.980 mm
(.1955 in to .1961 in)
570
engine
SERVICE
LIMIT
4.930 mm (.1941 in)
NEW
5.472 mm to 5.486 mm
(.2154 in to .216 in)
850 and
1000R
engines
SERVICE
LIMIT
5.450 mm (.2146 in)
Inspecting the Valve Face and Seat
1
R400m
o
tr84A
3
2
1. Valve seat
2. Exhaust valve contaminated area
3. Valve face (contact surface to valve seat)
Check valve face and seat for burning or pitting
and replace valve or cylinder head if there are
signs of damage.
Ensure to seat valves properly. Apply some lap-
ping compound to valve face and work valve on
its seat with a lapping tool (see
VALVE GUIDES
in
this subsection).
Measure valve face contact width.
NOTE:
The location of contact area should be in
center of valve seat.
Measure valve seat width using a caliper.
VALVE SEAT CONTACT WIDTH
EXHAUST VALVE
NEW
1.25 mm to 1.55 mm
(.049 in to .061 in)
SERVICE LIMIT
2.00 mm (.079 in)
INTAKE VALVE
NEW
1.05 mm to 1.35 mm
(.041 in to .053 in)
SERVICE LIMIT
1.80 mm (.071 in)
If valve seat contact width is too wide or has dark
spots, replace the cylinder head.
vmr2016-033-003_a
A. Valve seat contact width
Installing the Valve
Reverse the removal procedure. Pay attention to
the following details.
Install a
NEW
valve stem seal. Make sure thrust
washer is installed before installing seal.
Apply engine oil on valve stem and install it.
NOTICE
Be careful when valve stem is
passed through sealing lips of valve stem
seal.
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17