Motocross

Kawasaki KX450 2025

Motocross, 449cc 4T, US version

Partly verified

From the owner’s manual: engine oil capacity 0.9 L (1.0 US qt), p. 52; coolant 1.1 L (1.2 US qt), p. 55; front tire 80/100-21 51M, p. 13; rear tire 120/80-19 63M, p. 13. Checked 16 Oct 2026.

Safety recall 25-238

Safety recall, 2025-04-24

CPSC recall 25-238

Announced by Kawasaki Motors USA for Model Year 2025 KX series competition and cross-country motorcycles. It names the 2025 KX450.

Hazard: The primary gear for the crank shaft can fail, posing a crash hazard.
Remedy: Consumers should immediately stop using the recalled competition and cross-country motorcycles and contact a Kawasaki dealer for a free repair.
Units: About 3,400

A recall can cover only part of a model year, by VIN range. Check the notice, or give a dealer your VIN.

Read CPSC notice 25-238 All dirt bike recalls

Kawasaki KX450 2025

Workshop card from motoxsports.com/bikes/kawasaki-kx450-2025/ · each figure as the maker’s document prints it, with its source number; ≈ marks a figure we converted. Torque values are not published: use the manual.

Gearing

3 of 5 filled

Stock front sprocket: 13T; Verified, read off the manual page: Manual p. 12 · checked 2026-10-14 source [1]
Stock rear sprocket: 50T; Verified, read off the manual page: Manual p. 12 · checked 2026-10-14 source [1]
Chain pitch: Not yet verified
Stock chain links: Not yet verified
Stock final drive ratio: 3.846 : 1; Verified, read off the manual page: Manual p. 12 · checked 2026-10-14 source [1]

Wheels and tires

4 of 4 filled

Front rim: 21 x 1.60; Verified, read off the manual page: Manual p. 13 · checked 2026-10-14 source [1]
Rear rim: 19 x 2.15; Verified, read off the manual page: Manual p. 13 · checked 2026-10-14 source [1]
Front tire: 80/100-21 51M; Verified, read off the manual page: Manual p. 13 · checked 2026-10-14 source [1]
Rear tire: 120/80-19 63M; Verified, read off the manual page: Manual p. 13 · checked 2026-10-14 source [1]

Suspension

3 of 7 filled

Fork: Telescopic fork (upside-down); Verified, read off the manual page: Manual p. 13 · checked 2026-10-14 source [1]
Fork travel: 305 mm (12.0 in.); Verified, read off the manual page: Manual p. 13 · checked 2026-10-14 source [1]
Shock travel: 307 mm (12.1 in.); Verified, read off the manual page: Manual p. 14 · checked 2026-10-14 source [1]
Stock fork spring rate: Not yet verified
Stock shock spring rate: Not yet verified
Static sag, bike only: Not yet verified
Race sag, rider on: Not yet verified

Fluids and capacities

4 of 4 filled

Engine oil spec: SAE 10W-40; API SG, SH, SJ, SL or SM with JASO MA, MA1 or MA2; Verified, read off the manual page: Manual p. 12 · checked 2026-10-14 source [1]
Engine oil capacity (when filter is removed): 0.9 L (1.0 US qt); Verified, read off the manual page: Manual p. 52 · checked 2026-10-14 source [1]
Coolant capacity: 1.1 L (1.2 US qt); Verified, read off the manual page: Manual p. 55 · checked 2026-10-14 source [1]
Fuel capacity: 6.2 L (1.6 US gal); Verified, read off the manual page: Manual p. 11 · checked 2026-10-14 source [1]

Service specs

6 of 6 filled

Fork oil: Type Kawasaki Fork Oil A15-00; Amount: Cylinder Unit 248 mL (8.38 US oz.); Outer Tube KX450M 321 mL (10.9 US oz.); Verified, read off the manual page: Manual p. 14 · checked 2026-10-16 source [1]
Brake fluid: Front Brake Fluid : DOT4 or DOT5.1; Rear Brake Fluid : DOT4; Verified, read off the manual page: Manual p. 120 · checked 2026-10-16 source [1]
Coolant type: Permanent type of antifreeze (ethylene glycol plus corrosion and rust inhibitor chemicals for aluminum engines and radiators); Water and Antifreeze Mixing Ratio 1:1 (water:antifreeze); Verified, read off the manual page: Manual p. 55 · checked 2026-10-16 source [1]
Fuel octane: Antiknock Index 90; Verified, read off the manual page: Manual p. 26 · checked 2026-10-16 source [1]
Idle speed: 2 250 – 2 350 r/min (rpm); Verified, read off the manual page: Manual p. 74 · checked 2026-10-16 source [1]
Valve clearance: Intake 0.08 – 0.12 mm (0.0031 – 0.0047 in.); Exhaust 0.14 – 0.18 mm (0.0055 – 0.0071 in.); Verified, read off the manual page: Manual p. 102 · checked 2026-10-16 source [1]

Maintenance

3 of 3 filled

Tire pressure (off-road): 100 – 125 kPa (1.0 – 1.2 kgf/cm², 14 – 18 psi); Verified, read off the manual page: Manual p. 167 · checked 2026-10-14 source [1]
Chain slack: 48 – 54 mm (1.9 – 2.1 in.); Verified, read off the manual page: Manual p. 108 · checked 2026-10-14 source [1]
Spark plug and gap: NGK CPR8EB-9; Verified, read off the manual page: Manual p. 12 · checked 2026-10-14 source [1]

Dimensions

2 of 3 filled

Seat height: Not yet verified
Wheelbase: 1 480 mm (58.27 in.); Verified, read off the manual page: Manual p. 11 · checked 2026-10-14 source [1]
Weight (curb Mass): 112.6 kg (248.3 lb); Verified, read off the manual page: Manual p. 11 · checked 2026-10-14 source [1]

Solid marks are owner's-manual pages; hollow marks are manufacturer web or spec-sheet figures still waiting on a manual page. Last reviewed 2026-10-16. Rows marked not yet verified are blank on purpose.

Buying parts

The stock sizes and specs this bike left the factory with, each with its source. Take them to any shop.

Retailer links below are affiliate links: we may earn a commission, at no cost to you, and it never changes the specs. Affiliate disclosure.

Sprockets: Stock front sprocket 13T Owner's manual p. 12Stock rear sprocket 50T Owner's manual p. 1213T front sprockets at MotoSport 50T rear sprockets at MotoSport
Tires: Front tire 80/100-21 51M Owner's manual p. 13Rear tire 120/80-19 63M Owner's manual p. 13Front tires 80/100-21 at MotoSport Tubes 80/100-21 at MotoSport Rear tires 120/80-19 at MotoSport
Engine oil: Engine oil spec SAE 10W-40; API SG, SH, SJ, SL or SM with JASO MA, MA1 or MA2 Owner's manual p. 12Engine oil capacity (when filter is removed) 900 ml (30.4 fl oz) Owner's manual p. 52Engine oil at MotoSport
Coolant: Coolant capacity 1100 ml (37.2 fl oz) Owner's manual p. 55Coolant at MotoSport

In stock at MotoSport

Prices from MotoSport’s catalog of Oct 14, 2026; check today’s price before you buy.

Front tire, stock size 80/100-21

Rear tire, stock size 120/80-19

Engine oil, stock viscosity 10W-40

Matched on viscosity only. The manual prints: SAE 10W-40; API SG, SH, SJ, SL or SM with JASO MA, MA1 or MA2. Check the label for the rest.

Spark plug, stock NGK CPR8EB-9

NGKSpark Plug - CPR8EB-9$8.96 ~~was $12.01~~ SaleBuy at MotoSport

Prices and stock from MotoSport's product catalog on Oct 14, 2026; they change, so check the price at MotoSport before you buy. Products are chosen by exact stock size, code or oil viscosity from the specs above, known brands first, then price. We have not tested them.

4 part specs not yet verified; see data coverage.

Use this bike

Tools for this bike

Compare with

Comparisons with other bikes use the newest model year on file: Kawasaki KX450 2026.

Other model years

All 3 model years, 2024 to 2026, side by side

Gearing calculator

Gearing for this bike

Put your current gearing in Setup A and the setup you are considering in Setup B. Everything updates as you type.

Start from a bike's stock gearing

Pick a bike to fill both setups with its stock sprockets.

Front sprockets 8–16 teeth, rear 34–60. Values outside that range are brought back to the nearest limit.

Setup A — what you run now

Front teeth

Rear teeth

Setup B — what you are thinking about

Front teeth

Rear teeth

Final drive ratio

— — : 1

—

Pull at the wheel—

Top speed—

Ratio change—

A —

B —

Taller · more speed Shorter · more pull

—

Changing the rear sprocket changes the chain length too. The chain length calculator works it out from the chain you have now, with where the axle ends up.

Ratios are exact. The chain figure is an estimate of roughly one link per two teeth of change — confirm against your manual before ordering.

What's missing

24 of 31 fields read off a manual page.

Not yet verified (7): chain pitch, chain links, fork spring rate, shock spring rate, static sag, race sag, seat height.

See coverage for every bike

Sources

1
Kawasaki Owner's Manual, OWNER'S MANUAL, KX450M/N (2025), item 99814-0003 (© 2024 Kawasaki Motors, Ltd., Feb. 15, 2024 (1)); Kawasaki e-book on pws.ktivs.net, opened from the kawasaki.com owner portal; no model year printed, Kawasaki's own owner's manual portal lists it for model year 2025 (owner decision 2026-10-12)pp. 11, 12, 13, 14, 26, 52, 55, 74, 102, 108, 120, 167Manual page, verified. Covers stock front sprocket, stock rear sprocket, stock final drive ratio, front tire, rear tire, front rim, rear rim, fork, fork travel, shock travel, engine oil spec, engine oil capacity (when filter is removed), coolant capacity, fuel capacity, tire pressure (off-road), spark plug and gap, chain slack, wheelbase, weight (curb Mass), engine oil figure, as labelled, weight, as labelled, fork oil, brake fluid, coolant type, fuel octane, idle speed, valve clearance; checked 2026-10-16.

Always confirm against the manual for your exact year before ordering parts or setting up suspension. Torque specs are deliberately not published here. How we verify a value.

Your manual prints something different? Report a value with the page it is on; every fix is listed in the corrections log.

My settings

Date / track
Sprockets run
Race sag / free sag
Fork air pressure or spring
Fork clickers (compression / rebound)
Shock clickers (low / high / rebound)
Tire pressures (front / rear)
Notes

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