User manual YAMAHA WR250F-2003

[. . . ] Congratulations on your purchase of a Yamaha WR series. This model is the culmination of Yamaha's vast experience in the production of pacesetting racing machines. it represents the highest grade of craftsmanship and reliability that have made Yamaha a leader. This manual explains operation, inspection, basic maintenance and tuning of your machine. [. . . ] First tighten the bolts on the front side of the handlebar holder, and then tighten the bolts on the rear side. LUBRICATION To ensure smooth operation of all components, lubricate your machine during setup, after break-in, and after every race. Ç Lubricate the following areas with high quality, lightweight lithium-soap base grease. Wipe off any excess grease, and avoid getting grease on the brake discs. Q Insulator color 2 Normal condition is a medium to light tan color. Distinctly different color Check the engine condition. NOTE: When the engine runs for many hours at low speeds, the spark plug insulator will become sooty, even if the engine and carburetor are in good operating condition. Clean the plug with a spark plug cleaner if necessary. WARNING Since the headlight bulb gets extremely hot, keep flammable products and your hands away from the bulb unit it has cooled down. Install: q Headlight bulb Secure the new headlight bulb with the headlight bulb holder. Avoid touching the glass part of the headlight bulb to keep it free form oil, otherwise the transparency of the glass, the life of the bulb and the luminous flux will be adversely affected. If the float height is not within specification, inspect the valve seat and needle valve. Inspect: q Diaphragm (air cut valve) 1 q Spring (air cut valve) 2 q Air cut valve cover 3 q O-ring 4 Tears (diaphragm)/damage Replace. Install: q Washer 1 q Circlip 2 NOTE: Make sure the stopper a of the spring 2 fits into the recess b in the carburetor. Q Make sure the stopper c of the spring fits into the recess in the carburetor. Q Turn the throttle shaft assembly left while holding down the lever 1 5 and fit the throttle stop screw tip d to the stopper e of the throttle shaft assembly pulley. Install: q Push rod 1 2 1 NOTE: While holding down the lever 1 2, insert the push rod farthest into the carburetor. Install: q Valve seat q Screw (valve seat) 1 q Needle valve 2 q Float 3 q Float pin 4 NOTE: q After installing the needle valve to the float, install them to the carburetor. Install: q Pilot screw 1 q Spring 2 q Washer 3 q O-ring 4 Note the following installation points: q Turn in the pilot screw until it is lightly seated. Q Turn out the pilot screw by the number of turns recorded before removing. Install: q Diaphragm (air cut valve) 1 q Spring (air cut valve) 2 q O-ring 3 q Air cut valve cover 4 q Screw (air cut valve cover) 5 Install: q Diaphragm (accelerator pump) 1 q Spring 2 q O-ring 3 q Accelerator pump cover 4 q Bolt (accelerator pump cover) 5 NOTE: Install the diaphragm (accelerator pump) with its mark a facing the spring. Install: q Carburetor breather hose 1 NOTE: Install the carburetor breather hoses to the carburetor so that the hoses do not bend near where they are installed. [. . . ] Å Coverage of spring by weight i Rider weight 1 Soft 2 Standard 3 Stiff Front fork setting parts q Adjustment washer 1 TYPE (thickness) T = 2. NOTE: q The unequal pitch spring is softer in initial characteristic than the equal pitch spring and is difficult to bottom out under full compression. Rear suspension setting The rear suspension setting should be made depending on the rider's feeling of an actual run and the circuit conditions. Place a stand or block under the engine to put the rear wheel above the floor, and measure the length a between the rear wheel axle center and the rear fender holding bolt. [. . . ]