3. INSPECTION/ADJUSTMENT MXU 250R/300R Valve Wrench Loosen the lock nut and adjust by turning the adjusting nut Special tool: Tappet adjuster E012 · Check the valve clearance again after the lock nut is tightened. Round Hole CARBURETOR IDLE SPEED · The engine must be warm for accurate idle speed inspection and adjustment. Warm up the engine before this operation. Start the engine and connect a tachometer. Turn the throttle stop screw to obtain the specified idle speed. Idle Speed: MXU 250: 1500100 rpm MXU 300: 1600100 rpm Air Screw Throttle Stop Screw When the engine misses or run erratic, adjust the air screw. IGNITION TIMING Timing Hole Cap Index Mark The ignition unit is not adjustable. If the ignition timing is incorrect, check the ignition system. Remove the timing hole cap. Check the ignition timing with a timing light. When the engine is running at idle speed, the ignition timing is correct if the "F" mark on the flywheel aligns with the index mark Timing Hole on the right crankcase cover. 3-9