Engine

Numerous refinements to the liquid-Engine/Transmission

- Head gasket changed from metal gasket to O-rings for improved sealing and more accurate deck height

- New intake design features a single port with modified length and angle for improved intake efficiency

- Scavenging port exit angle is changed for improved scavenging efficiency, and the crankcase mating area around the scavenge ports has been increased. Third scavenging port also modified for improved flow

- New reed valve angle, air guide and reed block are changed for improved throttle response

- Intake air duct is reshaped to suite revised intake manifold

- New expansion chamber dimensions and improved construction (changed from four-piece to a three-piece) contributes to improved engine performance

- Redesigned piston uses new rings and new piston sealing grooves to prevent ring snagging; stronger pin boss improves durability

- Clutch release shaft and lever modified, and release mechanism moved behind generator cover

- Shift performance improved by using involute splines on the fifth gear and on the output shaft.  A needle bearing added to the shift shaft improves shift feel

- New water pump uses new pump gear ratios and a new impellor for increased coolant circulation, plus a new water jacket around the exhaust port eliminates the need for an external coolant hose

- Sprocket cover, governor cover, inner/outer clutch covers, and water pump cover changed to suit new crankcases

- Generator cover changed from plastic to magnesium for improved appearance and increased functionality

- Revised carburetor settings contribute to improved throttle response, and a new carb holder allows straighter incoming airflow

- Radiator core length increased (from 220 to 240 mm) for improved cooling performance

- Upgraded ignition system features increased condenser capacity and a generator with a built-in regulator for light weight. Stator shape changed, and new wiring harness used. Ignition timing changed to suit new power characteristics

- New, shorter spark plug eases maintenance and weighs less

- New, lightweight ignition coil is more compact

- Ignition coil primary terminals feature waterproof couplers for increased reliability

- Low-friction throttle barrel also reduces throttle operating friction

Rider Controls

- Stainless throttle cable wire with a greater number of  thinner strands delivers superb, low-friction throttle operation

- Clutch cable outer liner changed from polyethylene to Teflon for reduced friction

- Clutch adjuster added to clutch lever perch

- New front brake lever has better feel

Chassis/Suspension

- Steering rake reduced to 26 degrees to quicken steering response

- Footpegs are wider and offer better grip; shorter transverse length means greater cornering clearance

- Wider handlebar mounts (increased from 90 to 98 mm) help prevent handlebar bending

- New lightweight DID front rims with lightweight spokes and nipples reduce unsprung weight

- New cross-section for rear rims also designed for light weight

- Light fork and shock mounting bolts and a new rear brake master cylinder with a unitized reservoir and shorter yoke (17.5 mm shorter than '04 KX250) contribute to light weight

- Fork mounting bolt locations changed on the top triple clamp for easier maintenance and stronger mounting

- New front brake pad material offers better feel and performance

- Chain guide roller now uses two bearings for greater durability

- Rear subframe has larger forged upper mounting brackets for improved durability

- Fuel tank filler outlet is increased form 37 to 46mm for easier fueling

Options (available through Kawasaki dealers)

- Carburetor tuning parts

- Ignition rotors with different inertial weights

- Larger 14T front sprocket

- Spark plugs of varying heat ranges

- 20-inch front wheel

- Solid brake discs

- Aluminum and steel rear sprockets

- Different fork and shock springs

- Steel spoke nipples

- Front and rear wheel assemblies