User manual YAMAHA WR250F SERVICE MANUAL

[. . . ] primarily for use by Yamaha dealers and their qualified mechanics. It is not possible to include all the knowledge of a mechanic in one manual. Therefore, anyone who uses this book to perform maintenance and repairs on Yamaha vehicles should have a basic understanding of mechanics and the techniques to repair these types of vehicles. Repair and maintenance work attempted by anyone without this knowledge is likely to render the vehicle unsafe and unfit for use. [. . . ] Remove the camshaft caps and then measure the width of the Plastigauge 1 . Measure: S camshaft journal diameter a Out of specification !Replace the cylinder head and the camshaft caps as a set. Camshaft journal diameter 22. 967 X 22. 980 mm (0. 9042 X 0. 9047 in) 5-12 CAMSHAFTS EAS00208 ENG CHECKING THE TIMING CHAIN, CAMSHAFT SPROCKETS, AND TIMING CHAIN GUIDES The following procedure applies to all of the camshaft sprockets and timing chain guides. Check: S timing chain 1 Damage/stiffness !Replace the timing chain and camshaft sprockets as a set. 2. Check: S camshaft sprocket More than 1/4 tooth wear a !Replace the camshaft sprockets and the timing chain as a set. a 1 / 4 tooth b Correct 1 Timing chain roller 2 Camshaft sprocket 3. Check: S timing chain guide (exhaust side) 1 S timing chain guide (intake side) 2 S timing chain guide (top side) 3 Damage/wear !Replace the defective part(s). EAS00210 CHECKING THE TIMING CHAIN TENSIONER 1. With the timing chain tensioner rod turned all the way into the timing chain tensioner housing (with the thin screwdriver still installed), install the gasket and the timing chain tensioner 2 onto the cylinder block. WARNING Always use a new gasket. Tighten the timing chain tensioner bolts 3 to the specified torque. Timing chain tensioner bolt 12 Nm (1. 2 mSkg, 8. 7 ftSlb) d. Remove the screwdriver, make sure that the timing chain tensioner rod releases, and then tighten the cap bolt to the specified torque. Turn: S crankshaft (several full turns clockwise) 8. Check: S "T" mark a Make sure the "T" mark on the pickup rotor is aligned with the crankcase mating sure face b. S camshaft sprocket match mark c Make sure the match marks on the camshaft sprockets are aligned with the crankcase mating surface d . Tighten: S camshaft sprocket bolts 1 24 Nm (2. 4 mSkg, 17 ftSlb) CAUTION: Be sure to tighten the camshaft sprocket bolts to the specified torque to avoid the possibility of the bolts coming loose and damaging the engine. 5-16 CAMSHAFTS ENG 10. Measure: S valve clearance Out of specification !Refer to "ADJUSTING THE VALVE CLEARANCE" in chapter 3. 5-17 CYLINDER HEAD EAS00221 ENG CYLINDER HEAD 1st 19 Nm (1. 9 mSkg, 14 ftSlb) 2nd 50 Nm (5. 0 mSkg, 36 ftSlb) 12 Nm (1. 2 mSkg, 8. 7 ftSlb) Order Job/Part Removing the cylinder head Intake and exhaust camshaft Engine bracket Cylinder head Cylinder head gasket Dowel pin Q'ty Remarks Remove the parts in the order listed. Refer to "ENGINE". 1 2 3 1 1 2 For installation, reverse the removal procedure. 5-18 CYLINDER HEAD EAS00222 ENG REMOVING THE CYLINDER HEAD 1. [. . . ] S If gasoline touches the engine when it is hot, a fire may occur. Therefore, make sure the engine is completely cool before performing the following test. 1. Insert the plug 1 to fuel return hose end. Put the end of the fuel hose into an open container. [. . . ]