2014 Honda CRF250R — Owner's Manual
Remember, idle speed adjustment is not a “cureall” for other problems in your engine’s PGM-FI system. Adjusting the idle speed will not compensate for a fault elsewhere. The engine must be at normal operating temperature for accurate idle speed adjustment. When pushed in, the fast idle knob acts as the idle adjustment screw.
Turning it counterclockwise results in a faster/ higher idle speed. Turning it clockwise results in a slower/lower idle speed. Excessive valve clearance will cause noise and eventual engine damage. Little or no clearance will prevent the valve from closing and cause valve damage and power loss.
Check valve clearance when the engine is cold at the intervals specified in the Maintenance Schedule (page 25). The checking or adjusting of the valve clearance should be performed while the engine is cold. The valve clearance will change as the engine temperature rises. Rotate the crankshaft by turning the primary drive gear bolt (2) clockwise until the punch mark (3) on the primary drive gear aligns with the index mark (4) on the right crankcase cover.
In this position, the piston may either be on the compression or exhaust stroke at TDC. If the crankshaft passed the punch mark, rotate the primary drive gear bolt clockwise again and align the punch mark with the index mark. The inspection must be made when the piston is at the top of the compression stroke when both the intake and exhaust valves are closed. This condition can be determined by moving the exhaust rocker arm (5).
If it is free, an indication that the valves are closed and that the piston is on the compression stroke. If it is tight and the valves are open, rotate the primary drive gear bolt 360° and realign the punch mark with the index mark.