Yamaha YZF-R1 2007 Service Manual

ENGINE3-11EAS20710MEASURING THE COMPRESSION PRES-SUREThe following procedure applies to all of thecylinders.NOTE:Insufficient compression pressure will result ina loss of performance.1. Measure:• Valve clearanceOut of specification → Adjust.Refer to "ADJUSTING THE VALVECLEARANCE" on page 3-4.2. Start the engine, warm it up for severalminutes, and then turn it off.3. Disconnect:• Ignition coils4. Remove:• Ignition coils• Spark plugsCAUTION:ECA13340Before removing the spark plugs, use com-pressed air to blow away any dirt accumu-lated in the spark plug wells to prevent itfrom falling into the cylinders.5. Install:• Compression gauge “1”• Extension6. Measure:• Compression pressureOut of specification → Refer to steps (c)and (d).▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼a. Set the main switch to “ON”.b. With the throttle wide open, crank theengine until the reading on the compres-sion gauge stabilizes.WARNINGEWA4C81007To prevent sparking, ground all speak plugleads before cranking the engine.NOTE:The difference in compression pressurebetween cylinders should not exceed 100 kPa(1 kg/cm², 14 psi).c. If the compression pressure is above themaximum specification, check the cylinderhead, valve surfaces and piston crown forcarbon deposits.Carbon deposits → Eliminate.d. If the compression pressure is below theminimum specification, pour a teaspoonfulof engine oil into the spark plug bore andmeasure again.Refer to the following table.▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲7. Install:• Spark plugs• Ignition coilsCompression gauge90890-03081Engine compression testerYU-33223Extension90890-04136Standard compression pres-sure (at sea level)1480 kPa/350 r/min (210.5 psi/350 r/min) (14.8 kgf/cm²/350 r/min)Minimum–Maximum1290–1660 kPa (183.5–236.1psi) (12.9–16.6 kgf/cm²)Compression pressure (with oil applied intothe cylinder)Reading DiagnosisHigher than withoutoilPiston ring(s) wear ordamage → Repair.Same as without oil Piston, valves, cylin-der head gasket orpiston possibly defec-tive → Repair.Spark plug13 Nm (1.3 m·kg, 9.4 ft·lb)Manuals by Motomatrix / www.motomatrix.co.uk / The Solution For Lost Motorcycle Coded Keysemail: info@motomatrix.co.uk