Engine:

• New clutch plates enhance reliability
  
• Single piston ring
  
• New broader powerband characteristics is more rideable -delivers slightly less peak-power when compared to 2003 model
  
• Special SX ignition cover reduces engine weight
  
• Exhaust port system timing adjusted for smoother power delivery
  
• New crankshaft with increased oscillating mass offers better traction and more tractable power output
  
• New carburetor setting for smoother power delivery
  
• V-Force Intake System reed case for more accurate response

Exhaust:

• New exhaust pipe and silencer designed for increased torque and results in a more usable powerband

Frame:

• High-end chromoly frame features reduced wall thickness and lower overall weight – total frame weight now less than 9 kg (20 lbs.)
  
• New forged swingarm support and footpegs similar to 250 SX 2003 result is narrower, flatter profile and reduced weight
  
• Reinforced steering head area affords more reliability

Swing arm:

• Swing arm pivot increased 2 mm to 17 mm diameter (stiffer and lighter weight)
  
• 10 mm longer in all 2004 models offers more traction and more room for the rear wheel

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 through use of an optimal setting and a linear wound main spring

Front Brakes:

• All SX models have new brake discs with round holes for weight reduction, less wear and reduced operating temperature

Rear Brakes:

• All models have the same foot brake-cylinder (integrated reservoir) and the same brake calliper (26 mm) as 250 SX 2003

Wheels / Tires:

• Excel Rims
  
• Bridgestone M 59 and M 70 tires

Body Work:

• One-piece rear fender / side panel combination – same as last year's 250 SX and 450 SX – for all models
  
• Lower sub-frame assures optimal handling
  
• All seats feature a new seat base, anchored by a single mounting bolt located underneath the seat
  
• New larger airbox to accommodate one-piece tail section
• New air filter carrier with triple mounting pins for more reliability

Instruments / Controls:

• Renthal 608 tapered handlebar (12 mm higher than last year)
  
• Clutch master cylinder diameter reduced for less force and better clutch control (2-Stroke: reduced from 10.5 to 9.5 mm and 4-Stroke: reduced from 9.5 to 9.0 mm)
  
• Dual-component Renthal grips, grey/orange (smoother and more resilient to damage)

Trim / Graphics:

• New decals for spoiler and airbox cover - seat color remains solid black
  
• New frame guards