Honda CRF450RX 2020 User Manual

Engine Idle Speed
72 Servicing Your Honda
Engine Idle Speed
Refer to Important Safety Precautions on page 23.
Remember, idle speed adjustment is not a “cure
-
all” 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.
1. If the engine is cold, start it and warm it up 3
minutes. Then shut it off.
2. Connect a tachometer to the engine.
3. Shift the transmission into neutral. Start the
engine.
4. Adjust idle speed with the fast idle knob (1).
Idle speed: 2,000 ± 100 rpm
Idle Speed Adjustment
(1) fast idle knob
(+) increase
(–) decrease
(1)
(–)
(+)

Honda CRF450RX 2020 Specifications

General

Engine Type	449cc liquid-cooled single-cylinder four-stroke
Bore x Stroke	96.0mm x 62.1mm
Compression Ratio	13.5:1
Induction	Programmed Fuel Injection (PGM-FI), 46mm throttle body
Ignition	Full transistorized ignition
Transmission	5-speed
Final Drive	Chain
Front Brake	Single 260mm disc with twin-piston caliper
Rear Brake	Single 240mm disc
Front Tire	80/100-21
Rear Tire	120/80-18
Wheelbase	58.3 inches
Seat Height	37.8 inches
Ground Clearance	12.9 inches
Starter	Electric
Trail	4.6 inches
Front Suspension	49mm inverted fork with rebound and compression damping adjustability; 12.0 inches travel
Rear Suspension	12.4 inches of travel
Valve Train	Unicam, four-valve