The Garage

Motocross

Stock-size parts in stock at MotoSport

Kawasaki KX450F 2006–2008

Motocross, 449cc 4T

Verified

Illustration: a Kawasaki motocross bike, not this exact model.

From the owner’s manual: engine oil capacity 1.2 L (1.3 US qt), p. 1-8; front tire 90/100-21 57M, p. 1-9; rear tire 120/80-19 63M, p. 1-9. Checked 25 Sep 2026.

Model year on file: 2006–2008 only. Other years are added as their manuals are read.

No CPSC recall found for the 2006–2008 Kawasaki KX450F, checked 2026-10-15. Recalls

Spec card PDF

Gearing

4 of 5 filled

Stock front sprocket
13T
Verified, read off the manual page: Manual p. 1-9 · checked 2026-09-25 source [1]
Stock rear sprocket
50T
Verified, read off the manual page: Manual p. 1-9 · checked 2026-09-25 source [1]
Chain pitch
520
Verified, read off the manual page: Manual p. 2-34 · checked 2026-09-25 source [1]
Stock chain links
Not yet verified
Stock final drive ratio
3.85 : 1
Calculated, not printed: Calculated from the stock sprockets, printed on manual p. 1-9

Wheels and tires

4 of 4 filled

Front rim
21 x 1.60
Verified, read off the manual page: Manual p. 1-9 · checked 2026-09-25 source [1]
Rear rim
19 x 2.15
Verified, read off the manual page: Manual p. 1-9 · checked 2026-09-25 source [1]
Front tire
90/100-21 57M
Verified, read off the manual page: Manual p. 1-9 · checked 2026-09-25 source [1]
Rear tire
120/80-19 63M
Verified, read off the manual page: Manual p. 1-9 · checked 2026-09-25 source [1]

Suspension

2 of 7 filled

Fork
Not yet verified
Fork travel
315 mm (12.4 in.)
Verified, read off the manual page: Manual p. 1-9 · checked 2026-09-25 source [1]
Shock travel
315 mm (12.4 in.)
Verified, read off the manual page: Manual p. 1-9 · checked 2026-09-25 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

2 of 4 filled

Engine oil spec
Not yet verified
Engine oil capacity
1.2 L (1.3 US qt)
Verified, read off the manual page: Manual p. 1-8 · checked 2026-09-25 source [1]
Coolant capacity
Not yet verified
Fuel capacity
7.2 L (1.9 US gal)
Verified, read off the manual page: Manual p. 1-8 · checked 2026-09-25 source [1]

Maintenance

1 of 3 filled

Tire pressure (off-road)
Not yet verified
Chain slack
Not yet verified
Spark plug and gap
NGK CPR8EB-9
Verified, read off the manual page: Manual p. 1-8 · checked 2026-09-25 source [1]

Dimensions

2 of 3 filled

Seat height
965 mm (38.0 in.)
Verified, read off the manual page: Manual p. 1-8 · checked 2026-09-25 source [1]
Wheelbase
1 485 mm (58.46 in.)
Verified, read off the manual page: Manual p. 1-8 · checked 2026-09-25 source [1]
Weight
Not yet verified

Service specs

0 of 6 filled

Fork oil, brake fluid, coolant type, fuel octane, idle speed, valve clearance
Not yet verified
Solid marks are owner's-manual pages; hollow marks are manufacturer web or spec-sheet figures still waiting on a manual page. Last reviewed 2026-09-25. 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.

Chain
Chain pitch 520 Owner's manual p. 2-34520 chains at MotoSport520 master links at MotoSport
Sprockets
Stock front sprocket 13T Owner's manual p. 1-9Stock rear sprocket 50T Owner's manual p. 1-913T front sprockets at MotoSport50T rear sprockets at MotoSport
Tires
Front tire 90/100-21 57M Owner's manual p. 1-9Rear tire 120/80-19 63M Owner's manual p. 1-9Front tires 90/100-21 at MotoSportTubes 90/100-21 at MotoSportRear tires 120/80-19 at MotoSportTubes 120/80-19 at MotoSport
Engine oil
Engine oil capacity 1200 ml (40.6 fl oz) Owner's manual p. 1-8Engine oil at MotoSport

In stock at MotoSport

Prices from MotoSport’s catalog of Oct 26, 2026; check today’s price before you buy.

Front tire, stock size 90/100-21

Rear tire, stock size 120/80-19

Spark plug, stock NGK CPR8EB-9

Prices and stock from MotoSport's product catalog on Oct 26, 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.

5 part specs not yet verified; see data coverage.

Tools for this bike

Compare with

All 27 comparisons for this bike

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.

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
Setup B — what you are thinking about
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

14 of 31 fields read off a manual page.

Not yet verified (17): chain links, fork, fork spring rate, shock spring rate, static sag, race sag, engine oil spec, coolant capacity, weight, tire pressure (off-road), chain slack, fork oil, brake fluid, coolant type, fuel octane, idle speed, valve clearance.

See coverage for every bike

Sources

  1. 1
    Kawasaki KX450F Motorcycle Service Manual (KX450D6F-D8F, 2006-2008); owner-supplied copypp. 1-8, 1-9, 2-34Manual page, verified. Covers stock front sprocket, stock rear sprocket, chain pitch, front tire, rear tire, front rim, rear rim, fork travel, shock travel, engine oil capacity, fuel capacity, seat height, wheelbase, spark plug and gap; checked 2026-09-25.

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
All bikes