Checking The Valve Seats - Yamaha MTN1000 2016 Service Manual

Valve guide remover (ø4.5)
90890-04116
Valve guide remover (4.5 mm)
YM-04116
Valve guide remover (ø5)
90890-04097
Valve guide remover (5.0 mm)
YM-04097
Valve guide installer (ø4.5)
90890-04117
Valve guide installer (4.5 mm)
YM-04117
Valve guide installer (ø5)
90890-04098
Valve guide installer (5.0 mm)
YM-04098
Valve guide reamer (ø4.5)
90890-04118
Valve guide reamer (4.5 mm)
YM-04118
Valve guide reamer (ø5)
90890-04099
Valve guide reamer (5.0 mm)
YM-04099
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
3. Eliminate:
• Carbon deposits
(from the valve face and valve seat)
4. Check:
• Valve face
Pitting/wear  Grind the valve face.
• Valve stem end
Mushroom shape or diameter larger than the
body of the valve stem  Replace the valve.
5. Measure:
• Valve stem runout
Out of specification  Replace the valve.
TIP
• When installing a new valve, always replace
the valve guide.
• If the valve is removed or replaced, always re-
place the valve stem seal.
Valve stem runout
0.010 mm (0.0004 in)
VALVES AND VALVE SPRINGS
EAS30285

CHECKING THE VALVE SEATS

The following procedure applies to all of the
valves and valve seats.
1. Eliminate:
• Carbon deposits
(from the valve face and valve seat)
2. Check:
• Valve seat
Pitting/wear  Replace the cylinder head.
3. Measure:
• Valve seat contact width "a"
Out of specification  Replace the cylinder
head.
Valve seat contact width (intake)
0.90–1.10 mm (0.0354–0.0433 in)
Limit
1.6 mm (0.06 in)
Valve seat contact width (ex-
haust)
1.10–1.30 mm (0.0433–0.0512 in)
Limit
1.8 mm (0.07 in)
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Apply blue layout fluid "b" onto the valve face.
5-30