Yamaha’s 2003 four strokes!

Yamaha released information today about their 2003 four stroke race machines. It looks as though the engineers at under the big blue tent have done their homework. The 2003 YZ250F is 6.6lbs lighter than the 02 model and features 110 changes in 2003 model–49 in the engine and 61 chassis.

[IMAGE 1]

As for the big bore bike, Yamaha answered the call and increased the size of the engine from 426cc’s to 450cc’s. Not only did they make the bike faster, they made it lighter–232 pounds! That is one pound lighter than the aluminum framed CRF450! Some of the ways they made it lighter-a four-speed transmission, a titanium head pipe and aluminum oil lines. All together the new big bore sports 185 changes over the 02 version–112 in the engine, 73 in the chassis

Here are the details:

[IMAGE 2]

Engine-Pumping loss is reduced and carburetor setting is changed for more power

-New oil circulation system is used and oil volume is changed for weight reduction

-Automatic decompression governor system is used and hot starter position is changed for starting ability

-Newly designed crankshaft is used for reliability

-Oil strainer material is changed from brass to paper

Chassis

-Seat, fuel tank, side cover and rear fender is redesigned for riders mobility

-Main frame is improved for strength and weight reduction

-Rear frame pipe shape is changed for weight reduction

-Newly designed rear brake caliper and master cylinder is used for solid brake feeling

-Rear brake reserve tank is integrated with rear master cylinder

-New front fork and rear shock settings

-Newly designed handle crown is used for handling and stability

-Rear swingarm is changed to lighter smaller size and appearance is improved by anodized treatment

Electrical

-Smaller designed CDI unit is used and position changed

-Direct ignition coil is used

-1 piece type CDI magnet rotor is used

[IMAGE 3]

2003 YZ450F

Engine-4 stroke water cooled, 5 valve 450cc

-Increased stroke

2002 95×60.1

2003 95×63.4

-4 speed transmission

-Direct 16w coil

-Auto decompression

-Clutch damper

-Titanium head pipe

-Lighter crankshaft

-Lighter piston

-Shorter cam chain tensioner

-Smaller oil pump

-Aluminum oil lines

-Carburetor sealing and setting

Chassis

-Seat, fuel tank, side cover and rear fender is redesigned for riders mobility

-Newly designed rear brake caliper and master cylinder is used for solid brake feeling

-Newly designed handle crown is used for handling and stability

-Rear swingarm is changed to lighter and smaller size and appearance is improved by anodized treatment