2009 Yamaha YZ450F / YZ450FY Service & Repair Manual (P/N LIT-11626-22–57)

Yamaha’s 2009 YZ450FY Owner’s Service Manual, P/N LIT-11626-22-57, is the first edition dated May 2008. It covers YZ450FY configurations for the USA, Canada, Australia, and New Zealand, plus the YZ450F configurations for Europe and South Africa. Its seven chapters cover operation, maintenance, repair, electrical diagnosis, and tuning.

• Engine repair: Engine removal, cylinder-head and valve service, camshaft timing, crankcase separation, and crankshaft inspection.

• Clutch and shifting: Clutch disassembly and plate inspection, transmission reassembly, and kick shaft, shift shaft, shift cam, and shift fork service.

• Fuel and fluid systems: KEIHIN FCR-MX39 carburetor overhaul, accelerator-pump timing, radiator checks, and water-pump and oil-pump service.

• Suspension: Front fork rebuilding, swingarm and linkage bearing service, rear-shock spring replacement, and suspension setting charts.

• Brakes and running gear: Hydraulic brake bleeding, caliper and master-cylinder repair, steering-head bearing service, and drive-chain checks.

• Electrical diagnosis: Wiring diagram, ignition troubleshooting flowchart, CDI magneto tests, and throttle position sensor testing, replacement, and adjustment.

The repair sections assume existing Yamaha service knowledge and workshop skills; Yamaha recommends dealer maintenance for the front fork.

Engine Teardown and Valve Service

The five-valve DOHC top-end coverage includes valve-guide replacement, valve-seat inspection, camshaft measurements, and decompression-system checks. Intake and exhaust pad selection tables support valve-clearance adjustment. The accompanying notes address pad retention and keeping lifters and pads in their original positions.

Camshaft service cautions explain how uneven cap-bolt loading can damage the cylinder head, camshaft caps, and camshafts.

Internal engine work extends to crankshaft runout, connecting-rod clearances, transmission gear teeth and engagement dogs, and shift-fork grooves. Crankcase separation references tool YU-A9642 / 90890-04152. Exploded diagrams and job instruction charts accompany removal and disassembly, with sectional views clarifying assembly orientation.

FCR Carburetor, Cooling, and Lubrication

Carburetor procedures cover float-height measurement, needle-valve inspection, accelerator-pump components, and pump-timing adjustment. The tuning chapter explains how atmospheric conditions affect jetting and provides example settings for different throttle-response symptoms.

The leak-jet discussion distinguishes fuel delivery during rapid throttle opening from settings associated with steady throttle positions. This gives the mechanic a basis for interpreting response problems rather than treating every hesitation as an ignition fault.

Cooling and lubrication coverage includes radiator-cap and cooling-system pressure checks, water-pump shaft and seal inspection, oil-pump clearance measurements, and lubrication diagrams tracing oil delivery.

Fork, Shock, and Chassis Work

Front fork procedures include damper and base-valve inspection, seal replacement, oil filling, and air bleeding. An assembly caution identifies the risk of internal valve damage if the damper assembly drops into the inner tube.

Rear-shock work covers removal, spring and bearing replacement, preload, and damping adjustment. Yamaha warns against opening the nitrogen-filled cylinder or reservoir and assigns gas-release disposal work to Yamaha dealers. Chassis removal procedures also require secure machine support.

The “Suspension Setting” charts for the front fork and rear shock absorber relate handling symptoms to inspection and adjustment areas. Other chassis sections cover steering bearings, swingarm linkage, brake hydraulics, wheel inspection, and drive-chain slack and alignment. Cable routing diagrams show hose, cable, and harness placement during reassembly.

Ignition and Throttle Position Sensor Diagnosis

The wiring diagram identifies circuit connections and wire colors. Separate diagnostic flowcharts guide ignition and throttle position sensor checks, supported by connector views and tester connection illustrations.

The ignition fault path includes the engine stop switch, ignition coil, CDI magneto, neutral switch, and CDI unit. Electrical specifications distinguish CDI unit 34P-00 for the USA and Canada from 34P-10 for other markets.

Carburetor Setting and Charging-Coil Test Preview

The FCR-MX39 settings table specifies a #160 main jet and an NFLR needle in clip position 3, listed as NFLR-3. These are the documented standard settings alongside the manual’s tuning guidance.

CDI magneto testing separates charging coil 1, specified at 720–1,080 ohms, from charging coil 2 at 44–66 ohms. Both resistance ranges apply at 20°C (68°F).

Text Search, Bookmarks, and Diagram Detail

Search and diagram access: Most body text is searchable, while the valve-pad selection charts and warranty page are not text-searchable. Embedded bookmarks cover chapters and component sections; the table-of-contents entry has no active destination. Small wiring color codes are readable when enlarged.

Supplied as one printable English PDF with 276 pages, including 14 preliminary pages and one memo page.