By: Alex Lewis

-1974 Honda Elsinore One of the first 2 stroke purpose built motocross bikes.

-1990 Honda CR125

 Intake, Compression, Power Exhaust  Valves  Camshafts  Timing Chains

 1998 Yamaha YZ400m  1 st 4-stroke motocross bike.  Hard to start  Expensive  Heavy  Unreliable

 Bikes of today are equipped with:  Electronic Fuel Injection  Auto-Decompression  Aluminum Frames  Quieter Exhaust Systems  Advanced Suspension

 EFI  Electronic fuel injection is a form of electronically monitoring and measuring fuel within a internal combustion engine. The EFI system has an ECU or electronic engine control unit which, via a central processing unit (CPU) or microprocessor, accepts and registers the feedback from various sensors installed on the ATV and helps the ECU determine an appropriate output level. For example, the Yamaha YZ450f has seven sensors providing “real-time” feedback to its ECU’s 16-bit CPU.

 Advantages:  Bikes are easier to start  Run better at extreme temperatures  Better throttle response

 Fuel Mapping  Control fuel delivery with laptop  Bikes have a 16bit CPU

 ZERO MX Electric Motocross Bike  Lithium Ion powered  Very Lightweight  Silent  No Pollution