New 450 Racing 4-Stroke:

• Easy to ride engine characteristics based on previous 400 Racing 4-Stroke engines but with a significant difference in power output.
  
• Same technical updates as 2004 Racing 4-Stroke engines - clutch, carburetor and single-tube exhaust (2 kg (4.4 lbs.) weight reduction)

Engine:

• Strengthened clutch plates offer better reliability
  
• One-piece flywheel

Exhaust:

• 2004 Racing 4-Stroke' s feature single-tube exhaust systems which increase bottom-end torque and reduce weight significantly
  
• New silencer features a smaller, lighter shape and design

Frame:

• High-end chromoly frame features reduced wall thickness and lower overall weight – now less than 9 kg (20 lbs.)
  
• New forged swingarm support and footpegs provide a narrower, lighter weight and flatter profile.
  
• Reinforced steering head area affords more reliability

Swingarm:

• Swingarm pivot increased 2 mm to 17 mm diameter (stiffer and less weight)
  
• 10 mm longer swingarm on all 2004' s delivers better traction and more room for rear wheel movement

Fork:

• Newly adjusted WP 48 mm USD fork features three bushings – fork is more supple and offers greater sensitivity

Shock:

• Improved sensitivity and increased bottoming resistance by use of an optimal setting and a linear wound main spring

Front Brakes:

• The MXC models have new brake discs with round holes for weight reduction, less wear and lower operating temperature

Rear Brakes:

• The MXC models feature similar brake discs to the SX with round holes
  
• MXC models share the same integrated reservoir foot brake-cylinder and 26 mm brake caliper as the 250 SX 2003

Wheels / Tires:
EU:

• DID rims
  
• High-end Pirelli MT 83 competition tires

Body work:

• One-piece rear fender / side panel combination –same as last year' s 250 SX and 450 SX –for all models
  
• Lower subframe for better handling
  
• All seats have a new seat base, anchored by a single bolt located underneath the seat
  
• New larger airbox to fit the new one-piece tail section

Instruments / Controls:

• All models have dual compound Renthal grips in grey/orange (smoother and more damage resistant)
• Magura tapered handlebar (same as 2003)
  Clutch master cylinder diameter reduced from 9.5 to 9.0 mm requires less force and offers better clutch control)
  
• Separate start button

Trim / Graphics:

• New decals for the spoiler and airbox cover – seat remains solid black
• New frame guards