In a bold move, Yamaha's all new 2010 YZ450F has thrown away the mould and created an entirely new deisgn concept aimed at taking motocross performance to the next level.

The standard approach to improving handing is to concentrate the motorcycle's heaviest components at its centre in order to achieve mass centralisation. But using conventional packaging techniques, this method has reached its limit. So the YZ450F development team took an entirely new approach in order to raise the bar to a new industry standard.

Fuel injection (FI) is the key to unleashing the YZ450F's true potential. It has allowed the development team to try an innovative new layout: a rearward-slanting engine with a straight intake tract mounted in a lightweight Bilateral Beam frame. To prove their theories, Yamaha engineers built a prototype featuring this new-generation packaging. The result is a machine that truly reconfigures the MX landscape.

Yamaha is a renowned innovator having already developed Monocross suspension and the new wave of 4-stroke motocrossers. But despite being the first manufacturer to feature the system in prototype form, fuel injection has taken a relatively long time to be intrduced on a production Yamaha MX bike. The reason is the desire to get it right first time. Replacing the carburettor with FI is a simple task. But the development team wanted to ensure that the whole machine was developed in synergy and that the advantages offered by fuel injection were maximised.

The development team used the design freedom made possible by FI to completely redesign the machine without compromise.

All new chassis
A new Bilateral Beam aluminium frame sits at the heart of the YZ450F development project. This is a similar concept to the YZ250F frame but the execution is very different.

The 450F frame was developed using a new structural analysis method that gives a responsive ride quality. The frame consists of sixteen components and is made using a revolutionary new semi solid die-casting technology High Solid Die Casting, which allows complex shapes to be made stronger, while also ensuring more consistency with other parts.

Thanks to this new-generation layout, both sides of the frame are more symmetrical, a characteristic which contributes significantly to overall chassis feeling. This gives a consistent response from the area around the steering head, in spite of the ever-changing impacts and forces applied to the frame. Regardless of the impacts it is subjected to, the rigidity balance delivers a consistent feel. The result is a frame that gives the rider excellent control of the machine and a superb sense of handling.

Supporting this revolutionary frame is a new suspension system. Both front and rear suspension units have more capacity, and the front fork has a 10mm longer stroke. This new, long-stroke fork is tuned for high traction under a variety of riding conditions and offers precise damping, particularly on the initial part of the stroke. Even more remarkable is the fork's supple operation when entering a corner. The rear suspension offers smooth damping to help prevent the rear of the bike from kicking up.

By moving the air cleaner box to the front of the tank, the mounting points for the rear suspension and swingarm can be moved forward towards the centre of the chassis. The swingarm is also very symmetrical, contributing further to the YZ450F's stable handling qualities.

The YZ450F's new-generation packaging exemplifies the synergy between engine and chassis. The highly symmetrical and very balanced Bilateral Beam aluminium frame not only has super stable handling, it allows use of a straight intake tract for improved intake efficiency, while the rearward-slanting cylinder contributes to mass centralisation. Because the locations of the intake and exhaust are reversed, the locations of the air cleaner box and fuel tank are also reversed. The more vertical fuel tank means the bike's centre of gravity is lower and the bike is less influenced by changes in fuel volume. The result is a less tiring riding experience and a bike that corners with less effort.

Back to the future
Engineers have always known that a straight intake tract delivers efficient cylinder filling. And being the heaviest part of a motorcycle, the position of the engine is critical to handling. To tackle these challenges, the YZ450F development team decided to reverse the locations for intake and exhaust and create an all-new engine layout.

The air cleaner box is now located where the tank was, so the intake tract can have a straight shot into the cylinder head. To achieve the proper exhaust pipe length from the rearward-slanting cylinder, the pipe twists in a coil before reaching the silencer.

The rearward-slanting cylinder with its downdraft intake offers other benefits in addition to improved intake efficiency. The most remarkable of these is how it upgrades the YZ450F's handling. One of the drawbacks of the 4-stroke engine is its comparatively heavy cylinder head. By slanting the cylinder rearwards, the engine's inertial mass is concentrated more towards the centre of the machine. The new layout also gave the engineers more freedom in locating the rear suspension.

The evolution in the bike's performance exceeded all expectations. When they tested their idea with a prototype machine the engineers realised how effective it was. As a result of its superior handling performance, the YZ450F is very stable during corner entry and corner exits, giving the bike a much lighter and more responsive feel. This allows the rider to open the throttle sooner and to keep it open longer. It is the synergy between engine and chassis the makes the YZ450F such a stellar performer.

Fuel injection has various other benefits, such as control over air/fuel mixtures in response to altitude and temperature changes. Also, a newly developed and easy-to-use plug-in FI setting tool is available as an aftermarket item. The YZ Power Tuner makes it easy for riders to adjust the fuel load and ignition map to suit their riding style and riding conditions.

Other benefits of the forward-mounted intake include cooler intake air because it is unheated by the engine, and cleaner air, because the dirt and dust kicked up by the rear tyre is further away from the intake system.

Good things come in small packages
Many riders who have test ridden the YZ450F commented on its superb ergonomics. The fit between the rider's legs and the bodywork is excellent. Even after hard riding sessions, there was little damage evident on the textured plastic parts which was another design goal. From a purely functional standpoint, the thin, lightweight and small-area bodywork also contributes to mass centralisation.

Seen from any angle, the YZ450F is a great looking motorcycle — the pinnacle of new-generation packaging and functional beauty. As a visual expression of performance the YZ450F exemplifies the Yamaha design philosophy.

YZ450F main features
â–  Engine
1) Newly designed liquid-cooled 4-stroke, DOHC, single-cylinder 4-valve engine
The newly developed engine on this model is designed and engineered to provide power development characteristics that make for better drivability for a 450cc motocrosser while also contributing to better centralisation of machine mass. This engine features a compact 4-valve combustion chamber with a bore × stroke of 97.0 × 60.8 mm. The bore has been widened by 2 mm and the stroke shortened by 2.6 mm compared to the existing model.

For the compact combustion chamber, the two intake valves have a diameter of 36 mm and the two exhaust valves have a diameter of 30 mm and the valves' pinch angle is reduced to 21.5 degrees compared to the existing model. This creates a compression ratio of 12.5:1 (compared to 12.3:1 on the existing model). This shortened stroke reduces the height of the engine for better centralisation of machine mass while also providing the required power development character for a 450cc motocrosser. The 4-valve configuration enables the spark plug to be positioned in the centre of the combustion chamber, and the chamber itself is designed to create an effective air-fuel mixture tumble effect for better combustion performance that contributes to good response and power output. Also, the shapes of the ports have been optimised to provide better flow velocity.

The newly designed piston is a forged aluminium type and the cylinder is the same liner-less type as that of the existing model with ceramic composite plating, and the intake/exhaust valves are made of titanium like those of the 2009 model.

2) Unique fuel injected engine design with straight intake and rearward-slanting cylinder
A unique new fuel injected engine with straight intake and a rearward-slanting cylinder has been developed. This design has been realised by employing a combination of the latest fuel injection technologies and the Yamaha GENESIS engineering ideal that seeks to attain a high level of rider-machine communication by viewing the engine, chassis and all the components as parts of an organic whole in which everything functions to achieve total performance.

This innovative new layout defies the accepted concepts of chassis design and has introduced a new dimension of drivability not possible in a chassis developed for carburettor fed engines.

3) Front straight intake
The front straight intake directs air from the intake ducts on the right and left sides of the inside of the front air duct through the air cleaner positioned inside the frame and into the intake port, thus achieving excellent intake efficiency while also contributing to better centralisation of machine mass.

Also, because the intake ducts are positioned in front of the engine, heat from the engine has less effect on the intake air temperature and there is less chance of dust stirred up by the machine's wheels being drawn into the intake system.

In order to achieve this combination of straight intake and better centralisation of machine mass, the engine is mounted with a 7.5-degree rearward slanting of the cylinder. This also contributes to improved cornering performance.

4) Fuel injection that contributes to drivability
The fuel injection system is designed to make setting corrections to maintain optimum combustion demanded by a motocrosser under changing running conditions, including changes in engine temperature, air temperature and air pressure. To monitor changes in running conditions, the system is equipped with a throttle position sensor (TPS), intake pressure, intake air temperature, air pressure, crankshaft rpm and coolant temperature sensors.

Based on the data from these sensors, the compact ECU calculates the optimum induction fuel volume to accommodate changing conditions. For the fuel supply system, a compact, lightweight motocross-specific fuel pump has been adopted along with simplified periphery parts to save weight.

For the fuel delivery, a 12-hole injector is used and the spray of atomised fuel is directed at the opposite wall of the intake port at an optimum angle. This combines with the new port shapes to contribute to outstanding combustion efficiency. The distance between the injector and the intake valve has also been optimised and the combined effect with the large size intake valve diameter and the shape of the combustion chamber causes a positive flow tumble effect within the combustion chamber that increases combustion speed.

To accommodate the adoption of fuel injection, a large-capacity ACM (Alternating Current Magneto) has been adopted and the need for a battery eliminated to further reduce weight.

5) Rear Exhaust
The exhaust system is a rear-positioned type that passes under the seat. By adding curves to the exhaust pipe between the exhaust port and the muffler, it has been possible to maintain an exhaust pipe length comparable with that of the existing model while achieving better centralisation of machine mass. A resonator has also been fitted inside the exhaust pipe to ensure sufficient silencing effect while also bringing out excellent torque characteristics.

6) Offset cylinder adopted
By offsetting the cylinder 12 mm from the centre of the crankshaft, it has been possible to reduce friction loss and contribute to better engine characteristics.

Normally, when combustion forces the piston downward, there is also a lateral force component that pushes the piston toward the cylinder wall, resulting in friction between the piston and the cylinder wall. However, by offsetting the piston in a way that minimises piston and connecting rod slant at the moment of greatest combustion force, friction loss can be decreased.

This measure is called an offset cylinder, and it makes more efficient use of the force created by combustion. On this model, the amount of offset has been set to minimise the lateral force (pressure) component × piston speed in the target rpm range.

This marks the first time that an offset cylinder has been adopted on a Yamaha production off-road competition model.

7) Optimised oil tank shape
A dry sump with an oil tank in the crankcase has been adopted on this model since the 2006 model as a system that provides stable lubricating performance while also contributing to better centralisation of machine mass. For the 2010 model the oil tank volume has been kept the same but the shape has been changed to a vertically elongated type to minimise changes in the oil surface and promote air-liquid separation. This helps promote reliability. Also, a breather chamber has been added to the cylinder head to assure effective separation of the oil and blow-by gas and reduce oil consumption.

Changes have been made in the camshaft cover breather chamber shape and passages to help contribute to a lower engine height.

8) Lightweight parts introduced
For the head cover and clutch cover a heat-resistant magnesium alloy has been used to reduce weight while achieving a high-quality exterior look at the same time.

9) YZ Power Tuner FI setting tool accessory
A FI setting tool ‘YZ Power Tuner' has been developed as an option so the rider can adjust fuel injection volume and ignition timing to meet personal taste or course conditions. This is a compact tool with liquid crystal display that is small enough to fit in a pocket and has 1) a setting function and 2) a monitor function. The electric source is two AA batteries.

With the setting function, the user can adjust nine different setting points for fuel injection volume and ignition timing. Nine maps can be saved in the memory function on the tool.

Setting changes can be made easily without using a computer, simply by connecting the YZ Power Tuner to the coupler on the bike. The monitor function enables the user to monitor data from the various sensors, the engine running time and the malfunction self-diagnosis function for greater ease of maintenance.

The YZ Power Tuner is available from YMA as an aftermarket accessory.

â–  Chassis
1) New-design aluminium frame adopted
Taking advantage of the greater layout design freedom made possible with the adoption of FI, a newly designed Bilateral Beam aluminium frame with outstanding cornering performance has been adopted.

While taking full advantage of the Bilateral Beam frame's outstanding shock-absorbing capacity, this frame is also designed to contribute to a high level of handling performance by reducing inertial moment through improved centralisation of machine mass.

In particular, optimisation of the balance of strength, rigidity and flexibility makes it easier for the rider to feel the movement of the machine. This produces a ride that feels more stable and a bike that is easier to ride.

2) Optimum use of a variety of types of aluminium
Several types of aluminium (or processing methods) are used for the different parts of the frame depending on the balance of strength and rigidity required.

The frame is made up of 16 parts welded together into a single unit. A central point in creating this frame with its high-level balance of strength and rigidity is the adoption of a head pipe made by the High Solid Die Casting method in which the aluminium is shaped while still in a semi-solidified state. This High Solid Die Casting method makes it possible to form parts with complex shapes and achieve high-quality welds with the adjoining parts by enabling high-precision processing of the adjoining surfaces. This is a new production method developed jointly by Yamaha Motor's construction method research team and this model's development team.

For the right and left tank rails aluminium shaped by the hydro-forming method is used (see editor's note below). The materials used for the other parts include forged aluminum for the right and left arm tensioners and the upper half of the down-tubes, and extruded aluminium for the right and left halves of the lower parts of the down-tubes.

3) Rear shock absorber aligned on the machine's central axis
To accommodate the new frame, the rear suspension has also been newly designed. To provide effective response, especially when landing from a jump, the rear shock absorber has been positioned in line with the machine's central axis. This positioning has been made possible by the adoption of the frontal intake FI system and the accompanying placement of the air cleaner (in front of the engine), which enables more efficient use of space in the rear. Also, the position of the suspension spring has been moved about 30 mm lower.

The shock cylinder diameter has been increased from the existing 46 mm to 50 mm for greater capacity. The suspension stroke remains the same as on the existing model. And the bump rubber characteristics have been optimised to improve the absorption feeling when bottoming.

Optimisation of the valve that creates the damping force has given this new suspension a character that lets the rider feel the damping effect from the start of the compression stroke and provides good terrain-following performance.

4) New-design swingarm
The swingarm has been newly designed to achieve the best possible match for the new body and the positioning of the rear shock absorber along the central axis of the machine and thus help contribute to cornering performance that is even more linear in character. The basic design of the irregular cross-section swingarm is the same top-bottom asymmetrical design as that on the existing model.

Furthermore, the thickness of the rear axle clamp has been increased for greater rigidity. This combines with the optimised suspension settings to achieve a new level of cornering performance. To help realise the chassis design concept of good longitudinal flexibility and high lateral and torsional rigidity, the swingarm has been produced by the hydro-forming method just like that on the existing model.

5) Longer stroke front suspension
In order to improve shock absorption and smooth operation when entering a turn at high speeds, the damping valve specs have been optimised. The stroke has also been increased from 300 to 310 mm.

6) New dimension fork brackets
New parts with excellent rigidity properties have been adopted for the front fork brackets (handlebar crown and under-bracket). The offset has been reduced from 25 to 22 mm. The caster, trail and other dimensions have been optimised in relation to each other to help achieve a high-level of handling performance. The handlebar crown is made of cast aluminium and the under-bracket is made of forged aluminium.

The same 2009 model 4-step adjustable handlebar position features again. The axis of the handlebar bracket is offset and there are two attachment holes each for the handlebar crown (holder), which makes for a choice of four different handlebar mounting positions, two on the bracket side (forward/aft.) and two on the crown side (forward/aft.). This makes it possible to choose the desired setting based on rider preference or course conditions.

7) New-design flat seat
A new flat seat has been adopted that takes full advantage of the increased design freedom made possible by the adoption of fuel injection. The rigidity of the seat bottom and the structure at the point of load have been optimised for a better feel and sense of fit.

The seat surface material is the same as on the 2009 model. It is vinyl chloride with an optimised mix of compounds added to the smooth nylon base fabric to provide the right balance of grip and ease in sliding.

These qualities are especially felt when the rider starts to shift body weight on the seat and the secure grip when the rider needs a firm hold on the machine. The surface texture is designed to resist clogging of the surface grain with sand or mud to ensure superior grip and reduce the amount of dirt build-up after a ride.

8) Under-seat fuel tank
The lightweight plastic resin fuel tank features a new design. Placing the tank under the seat also contributes to better centralisation of machine mass and a lower center of gravity. This helps reduce the effect of changing fuel levels on the machine's handling.

9) Lightweight exterior parts newly adopted
This model adopts newly designed lightweight exterior parts. The new parts include the thinner front fender, rear fender, front number plate, front fork protector, side covers and air scoop etc.

Other lightweight parts include the new-design sprocket, a plastic resin engine guard (existing model has aluminium guard) and lightweight electrical parts.

10) Innovative design styling
New sculptural design elements feature that reflect the fast and nimble movement of this machine as well as smooth and agile cornering performance, the ease of rider movement by the flat seat and high-level handling potential enabled by the centralisation of machine mass. The result is a look that sets it apart as a new-generation motocrosser with styling that accentuates outstanding cornering performance. It also boasts the kind of structural and functional beauty and look of quality that is sure to make it stand out in the owner's garage like a work of art in a museum.

The overall sculptural design of the body is one that gives visual expression to the innovative new chassis layout. It is a sculptural design that accentuates the frontal air intake, the low centre of gravity of the fuel tank and the rear-mounted exhaust system.

The air scoop has a two-piece design consisting of the air intake (upper side) and the radiator guard (lower side) and well matched with the dynamic new look of the front fender.

The open space under the hip point of the seat makes it possible to see through to the view on the other side of the machine and give a clear expression of the high degree of centralisation of machine mass that has been achieved in this model.

Also, the crankcase cover (clutch cover and ACG cover) is designed for minimum interference with leg/foot movement. Its design is one that clearly separates the portions where the finish will and will not wear off in rugged riding where the rider's boot is scraping the cover hard enough to scratch the boot. The result is that even if the scraping of the boot causes the finish to become scratched and wear off to some degree, it will keep an overall impression of beautiful exterior parts.

11) Special Edition white
To further heighten pride of ownership, a white Special Edition version is offered as a second colour (pictured right).

12) Tyres
Dunlop 80/100-21 51M front and Dunlop 120/80-19 63M rear tyres are standard fitment to Australian spec models

YZ tuner offers simple trackside solutions
38 years after release of the first YZ model, revolutionary advances have been made in the new model YZ450F with the adoption of fuel injection.

Automatically controlling fuel supply in accordance with changes in air temperature, air pressure and other changes in the riding environment, the fuel injection system helps the rider concentrate on riding and expands the potential of the riding performance. It is all made possible by fuel injection.

Riders will always want to try different settings of their own, like a richer fuel-air ratio in the lower rpm range to get stronger traction, or a leaner mixture in the high-speed range for lighter revs, or richer mid-speed range to fit the demands of a particular course. Hidden somewhere in the settings may be hints to help riders reach the next level of performance.

A fuel injection system (FI) automatically adjusts the fuel supply in accordance with changes in the natural environment. But it can't adjust for things like track surface conditions or changes in the rider's physical condition. Plus there are many different types of courses that are ever-changing.

That is why the YZ450F development team at Yamaha wants all its new owners to not only experience the fun of performing engine setting themselves but also to increase their enjoyment of motocross riding by making adjustments to fit track conditions or their own personal preferences. That led the team to create an the YZ Power Tuner.

Invitation to the world of settings
It is through settings that riders can achieve the lightness of handling and agility they need for difficult course conditions caused by sand, hardpack, wind and rain. To take the hassle out of setting work, this new Power Tuner has been designed to eliminate the need for using a PC and all the extra care in handling and boot-up time it requires. It is also designed for optimum simplicity in the data transfer operation as well.

Greater ease of use also shortens the amount of time needed to reach the best settings. Also, for those riders who have been put off by the complex tangle of elements involved in carburettor setting, this Power Tuner holds the key to offering a first step into a new world where setting work is actually fun and the rewards immediate.

Dial in your own specs

To do this, the system includes a throttle position sensor (TPS), intake air temperature, coolant temperature, air pressure, intake pressure and crankshaft revolution sensors that provide the data enabling the compact ECU to calculate optimum fuel injection volume and actuate the injections.

This operation is supported by two 3-dimension program maps. These include (1) a fuel injection volume map and (2) a map determining ignition advance (ignition timing) characteristics, both of which include engine rpm and throttle opening as parameters. When it is shipped from the factory, YZ450F is set at a basic value (standard map) tuned to effectively bring out the engine's inherent performance potential in a wide range of riding conditions.

The settings that can be made with this Power Tuner are (1) fuel injection volume and (2) ignition advance (ignition timing) characteristics, and both of these are set as adjustments of the “standard map.†Using this tool you can create your own customised 3-D map for fuel injection volume and a 3-D map for ignition advance characteristics to fit your preferences.

On both maps there are three adjustable points, one each for the low-speed, mid-speed and high-speed ranges. And there are three points for throttle opening. Combined, there are 3×3 = 9 adjustable points. Thus for the two maps there are a total of 18 adjustable points.

For the fuel injection volume map, adjustments can be made over a range of 15 steps, from -7 to +7 compared to the standard map, at each of the nine points. In YZ450F, each step represents a change of 3% in the fuel injection volume, which means a maximum adjustment range of -21% to +21%. The adjustments for ignition advance character can be made over a range of 14 steps, from -9 to +4 compared to the standard map, at each of the nine points.

In YZ450F, each step represents a change of 1 degree in advance angle, which means a total adjustment range of -9° to +4°. Setting all nine points creates a map that passes smoothly through each point. These two maps, the (1) map for fuel injection volume and (2) the map for ignition advance characteristics, become one set that constitutes your own customized “FI setting map.â€

Riders are able to set a number of different types of customised settings for different types of riding conditions. The customised maps that are created in this way can then be saved on the Power Tuner memory function. Up to nine different sets of map data can be saved in files and plugged into the bike in seconds.

Maps in minutes
Once your customised map is created, the next step is to upload that data into the motorcycle. Stop the engine and connect the POWER TUNER to the coupler on the motorcycle to easily upload the data.

Turn on the Power Tuner and select “SETTING.†Then select “SEND.†Next, select the “MAP†you have saved on the tool. Check that contents on the MAP window to make sure it is the correct map and then press “OK†to upload the data into the motorcycle.

This completes the setting operation. Once you learn the process it takes no more than a minute to complete. No special tools or personal computer are needed. Once this simple upload process is complete, your setting is complete and you are ready to go out on the track and start riding.

The Power Tuner fits in the palm of the hand and is compact enough to fit in a large pocket. (Size – Length: 139mm, Width: 85mm, Thickness: 37mm) Also, you can create and save new map data on the tool wherever and whenever you want, at the track, in the garage, at home or when travelling.

Share the love
Once a rider has discovered the fun and satisfaction of riding the 2010 YZ450F with the customised settings, they can share them with YZ450F riding friends. The map data created on the Power Tuner can be input directly into a friends' YZ450F through the coupler with the same ease as inputting data into the fist owners' bike. By sharing settings in this way riders will be able to share opinions and perhaps make new discoveries.

Also, friends who have the Power Tuner can share settings that are working well for them, or a more experienced rider may pass on his FI settings too.

In this way, the Power Tuner is not only a valuable tool to help expand rider potential creating customised settings but also one that enables meaningful communication with like minded YZ450F riders.

Diagnostic functions included
The Power Tuner also features a number of monitor functions. The first feature is the record of engine running hours. This can be checked regularly as a guide for parts replacement and routine maintenance timing.

There is also a malfunctions check option, including the ECU, actuator and various sensors. With this function you can check the throttle position sensor (TPS) and the intake air temperature, coolant temperature, intake pressure, and crankshaft revolution sensors.

You can also connect the Power Tuner to the coupler on your machine just before a ride or during a pit stop to get real-time information on the machine's coolant temperature, intake air pressure, atmospheric pressure, etc. If the engine is stopped the rpm meter will read “0 r/min†and if the engine is started the monitor will show the idling rpm at around 2000 r/min.
This can then be used to adjust the idling rpm.

Being able to regularly check on sequential engine running time, a rider can keep records of things like how long they have run on a given day. They can check their running time and can compare records with other YZ450F owners to see who has put the most time on their machine.

Examples of mapping
Below is an example of two typical settings:

Setting for improved drivability
For riding in slippery conditions, such as on hard packed dirt or wet surfaces. This setting provides easier throttle work that can be experienced not only by experts but a wide range of YZ450F users.

Fuel Injection (FI)

Igntion (IG)

Setting for improved response
This setting is suited for a linear engine response to throttle work when riding on dirt with good traction or on high-load sand courses. This setting helps to achieve faster engine revving up through the rpm range for owners who want to ride more aggressively.

Fuel Injection (FI)

Igntion (IG)

2010 YZ450F key dimensions (v 2009)