By: Alex Lewis

-1974 Honda Elsinore 125- One of the first 2 stroke purpose built motocross bikes.

-1990 Honda CR125

Intake, Compression, Power ExhaustValvesCamshaftsTiming Chains

1998 Yamaha YZ400m1st 4-stroke motocross bike.Hard to startExpensiveHeavyUnreliable

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