Inside The All-New 2014 Yamaha YZ450F

After months of speculation, which were fueled by our sightings of works bikes in Japan, Yamaha has officially released their 2014 YZ450F. The bike is just what we spotted while covering the opening round of the All-Japan MX Nationals and uses the wrap-around exhaust system that was made by FMF Racing and first seen on JGRMX/Toyota/Yamaha bikes at last year’s Monster Energy Cup. Nearly every thing about this machine is all-new, and it features both a new engine and chassis that was designed for centralization of mass. The routing of the wrap-around exhaust brings the shock to a more traditional layout and pulls a massive amount of weight closer to the heart of the bike. Ergonomics and maintenance are both improved by fewer body panels, bolts, and a gas tank that is hidden underneath the seat.

Inside The All-New 2014 Yamaha YZ450F

2014 YAMAHA YZ450F ENGINE

An all-new engine is the heart of the 2014 YZF, and was designed to produce more power while remaining controllable. The list of new engine components includes:

• Exhaust system
• Piston
• Cylinder head that has straight-port down draft design
• Intake and exhaust valves
• Intake cam shaft
• Crankcase breather
• Water pump impeller
• ECU setting
• Crankcase wet-sump lubrication system
• Stronger clutch
• Transmission ratios
• Shift mechanism
• Gear Position sensor

A wrap-around exhaust system is the most eye-catching change to the 2014 Yamaha YZ450F. This concept was debuted last year by the JGRMX/Toyota/Yamaha team and FMF Racing at the recommendation of the Japanese OEM. It concentrates more weight to the front end so that the handling of the bike feels lighter and more responsive. The silencer has three different diameters on the inside for the best overall power.

The intake system has been redesigned and now uses a traditional-style filter that is housed in a larger air box. The volume of the air boot has been increased, but its new location reduces the noise of the air intake. These increases in airflow require changes to the fuel mapping and engine timing.
The diameter of the intake and exhaust ports have been increased (1mm on the intake valve and .5mm on the exhaust valve) and the shapes of both have been changed.
The crown of the piston is more shallow than the 2013 piston; this improves combustion and increases torque in the low to mid range of the powerband. A two-ring design and different surface coating reduce friction in the cylinder and improves throttle response.

The gear ratios of the transmission have been changed; the gap between second and third gear is closer and the gap between third and fourth is wider. A new shift lever and larger shift shaft diameter allow the rider to click through the gears with less resistance.
To handle the increased power output, the 2014 YZF clutch has been built 20-percent stronger than last year. The pressure of the clutch springs have been increased and the friction plate is made of a new material.
The engine cases have been made more compact and the engine’s lubrication system has changed from dry sump to wet sump. This allows the oil capacity to be reduced to .95 liters.

2014 YAMAHA YZ450F CHASSIS

Centralizing the mass was the focus of Yamaha engineers and they have designed an all-new chassis for the 2014 YZ450F. Changing the frame dimensions and altering construction in key areas improves the balance of the machine. Redesigned or revised areas of the chassis include:

• New frame
• New subframe
• New engine brackets
• New fuel tank
• New rear shock
• New fork settings
• Larger front axle
• Rubber mounted bar mounts
• New Dunlop MX51FA front tire

 

The frame itself has new dimensions in the steering tube, tension arm, and engine cradle and the thickness of the tank rails has been changed. The material of the engine brackets depends on their position; the top brackets are steel while the bottom are aluminum.

The suspension has undergone a number of major refinements. There is a change in to the rigidity of the outer tube and the surface finish of the inner tube, the layout of the rear shock to accommodate the fuel tank and exhaust, and both have revised settings to absorb impacts.

A more rigid top clamp holds the forks in place, and the four position handlebar mount is now rubber mounted into the clamp. The diameter of the front axle has been increased from 20mm to 22mm. These changes offer a more rigid feel while reducing vibration to the rider’s arms.

Bringing more weight lower and to the center of the bike is a new subframe and fuel tank. These parts drastically reduce the amount weight spread over the surface of the bike. The tank’s capacity has also been increased over a full liter and will now hold 7.5 liters of fuel.
The electrical center of the bike has been brought to the front and center of the frame. With all of the components much closer, the wire harness is now shorter.

Minimalism is the key to the ergonomics of the 2014 Yamaha YZ450F. A two-piece seat and the fuel tank’s placement allows the rider to move far forward without interference. Regular maintenance is a much simpler task, thanks to the revised airbox and fuel tank; both come apart and move out of the way with fewer tools. The total number of body pieces has been reduced to eight due to changes on the shrouds, side panels, and rear fender. The graphics are now embedded into the radiator shroud plastic and are impossible to peel off.
The 2014 YZ450F was designed for a rider to pilot it effortlessly around the track. A nimble chassis responds to a rider’s input and the motor is now more powerful while remaining broad and useable.

Posted by Transworld Motocross.net on June 12, 2013 in Yamaha |