Yamaha WR250F Owner's Service Manual

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Contents

ENGINE3-194. Measure:• Engine idling speedOut of specification  Regulate.5. Adjust:• Engine idling speed▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼a. Turn the starter knob/idle screw “1” in the di-rection of “a” or “b” to make an adjustment.▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲EAS2GB2101ADJUSTING THE VALVE CLEARANCETIP• This section is intended for those who havebasic knowledge and skill concerning the ser-vicing of Yamaha motorcycles (e.g., Yamahadealers, service engineers, etc.). Those whohave little knowledge and skill concerning ser-vicing are requested not to undertake inspec-tion, adjustment, disassembly, or reassemblyonly by reference to this manual. It may leadto servicing trouble and mechanical damage.• Make sure that the valve clearance ischecked or adjusted while the engine is cold(at room temperature).• While the valve clearance is checked or ad-justed, make sure that the piston is positionedin the top dead center (TDC).1. Remove:• Seat• Side cover (left/right)• Air scoop (left/right)Refer to “GENERAL CHASSIS” on page 5-1.• Fuel tankRefer to “FUEL TANK” on page 8-1.• ECU2. Remove:• Spark plug• Cylinder head coverRefer to “CAMSHAFT” on page 6-11.3. Remove:• Timing mark accessing screw “1”• Crankshaft end accessing screw “2”• O-ring4. Check:• Valve clearanceOut of specification  Regulate.▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼a. Turn the crankshaft counterclockwise with awrench.b. Align the top dead center (TDC) mark “a” onthe rotor with the alignment mark “b” on thecrankcase cover.Engine idling speed1900–2100 r/minDirection “a” Engine idling speed  De-creases.Direction “b” Engine idling speed  In-creases.1baValve clearance (cold)Intake0.12–0.19 mm (0.0047–0.0075 in)Exhaust0.17–0.24 mm (0.0067–0.0094 in)12ab