Engine Inspection; Measure The Compression Pressure - Yamaha YZF-R1 Series Service Manual
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- Owner's manual (130 pages) ,
- Service manual (92 pages) ,
- Manual (82 pages)
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EAS20041
ENGINE INSPECTION
EAS30249
MEASURE THE COMPRESSION PRESSURE
The following procedure applies to all of the cyl-
inders.
TIP
Insufficient compression pressure will result in a
loss of performance.
1. Measure:
• Valve clearance
Out of specification → Adjust.
Refer to "ADJUSTING THE VALVE CLEAR-
ANCE" on page 3-6.
2. Start the engine, warm it up for several min-
utes, and then turn it off.
3. Remove:
• Rider seat
Refer to "GENERAL CHASSIS (1)" on page
4-1.
• Fuel tank
Refer to "FUEL TANK" on page 7-1.
• Air filter case
Refer to "AIR FILTER CASE" on page 7-5.
• Air cut-off valve
Refer to "AIR INDUCTION SYSTEM" on
page 7-20.
• Ignition coils
• Spark plugs
Refer to "CAMSHAFTS" on page 5-18.
ECA13340
NOTICE
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.
4. Install:
• Compression gauge "1"
Compression gauge
90890-03081
Engine compression tester
YU-33223
ENGINE INSPECTION
1
5. Measure:
• Compression pressure
Out of specification → Refer to steps (c) and
(d).
Compression pressure
1261–1624 kPa/210 r/min (12.6–
16.2 kgf/cm²/210 r/min, 179.4–
231.0 psi/210 r/min)
a. Set the main switch to "ON".
b. With the throttle wide open, crank the en-
gine until the reading on the compression
gauge stabilizes.
EWA17100
WARNING
To prevent sparking the plug, remove all ig-
nition coil couplers and fuel injector cou-
plers before cranking the engine.
TIP
The difference in compression pressure be-
tween cylinders should not exceed 100 kPa (1
kgf/cm², 15 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
minimum specification, pour a teaspoonful
of engine 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
5-9
Diagnosis
Piston ring(s) wear or
damage → Repair.
Piston, valves, cylinder
head gasket possibly
defective → Repair.
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