Yamaha MT-01 T 2005 Service Manual page 95

1
5. Disconnect:
• Spark plug cap
6. Remove:
• Spark plug
ECA13340
CAUTION:
Before removing the spark plugs, use com-
pressed air to blow away any dirt accumulat-
ed in the spark plug wells to prevent it from
falling into the cylinders.
7. Install:
• Compression gauge "1"
• Extension "2"
Compression gauge
90890-03081
Engine compression tester
YU-33223
Extension
90890-04082
1
8. Measure:
• Compression pressure
Out of specification → Refer to steps (c) and
(d).
Standard compression pressure
(at sea level)
1200 kPa/200 r/min (170.7
psi/200 r/min) (12.0 kgf/cm²/200
r/min)
Minimum–maximum
1000–1400 kPa (142.2–199.1 psi)
(10.0–14.0 kgf/cm²)
2
3-10
M MMM M MMM M M MMM M
a. Set the main switch to "ON".
b. With the throttle wide open, crank the engine
until the reading on the compression gauge
stabilizes.
EWA12940
WARNING
To prevent sparking, ground all spark plug
leads before cranking the engine.
NOTE:
The difference in compression pressure be-
tween cylinders should not exceed 100 kPa (1
kg/cm², 14 psi).
c. If the compression pressure is above the
maximum specification, check the cylinder
head, valve surfaces and piston crown for
carbon deposits.
Carbon deposits → Eliminate.
d. If the compression pressure is below the min-
imum specification, pour a teaspoonful of en-
gine oil into the spark plug bore and measure
again.
Refer to the following table.
Compression pressure (with oil applied into
the cylinder)
Reading
Higher than without
oil
Same as without oil
L LLL L LLL L L LLL L
9. Install:
• Spark plug
Spark plug
18 Nm (1.8 m·kg, 13 ft·lb)
10.Connect:
• Spark plug cap
11.Connect:
• Decompression solenoid couplers
12.Install:
• Fuel tank
Refer to "FUEL TANK" on page 6-1.
• Seat
Refer to "GENERAL CHASSIS" on page 4-1.
ENGINE
M MMM M M MMM M M MMM M
Diagnosis
Piston ring(s) wear or
damage → Repair.
Piston ring(s), valves,
cylinder head gasket
or piston possibly
defective → Repair.
L LLL L L LLL L L LLL L
MMM
LLL