CDR Rockstar Yamaha 2010 YZ 450F

After covering the season launch, round-by-round coverage and interview with CDR's Jay Marmont, we take a closer look at the bike that helped Jay secure that record-equalling third championship - the 2010 Yamaha YZ 450F.

'Revolutionary' was a word often bandied about when describing the 2010-spec YZ 450 when it was launched in late 2009. In the case of this bike, however, it wasn't just advertising hype, as the new YZ450 does indeed boast a number of innovative, fresh ideas in terms of frame design, engine layout and packaging.

The addition of electronic fuel injection, while only part of the package, was significant as it allowed Yamaha designers more freedom in configuring the engine and surrounding componentry to achieve the best possible 'mass centralisation' (a term that refers to how much of the bike's overall weight is located in one spot - that is, under the rider). How well or how poorly this is achieved is largely down to engine packaging and positioning, as it's the heaviest part of the bike. Carb-fed bikes had reached the end of their development curve according to Yamaha, so fuel injection, while not new in itself, was the way to go to open up new possibilities to achieve the best possible mass centralisation.

The result in the 2010 YZ 450F is an engine that, at first glance, looks 'wrong'. There isn't the traditional rear-mounted carb, nor is there the typical exhaust layout where the pipe exits from the front, so the engine appears to be back to front. Additionally, instead of being vertical or sloping forward, the engine actually slants to the rear - 7.5 degrees, to be exact. This reverse slant places more of the engine under the rider, which in turn improves handling. The angle also means the connecting rod is vertical at the moment of greatest combustion force, which minimizes friction and delivers quicker throttle response. Despite being heavier than the 2009 model, the repackaging of the engine and surrounding componentry means the 2010 YZ 450F actually feels lighter than its predecessor.

The engine itself uses a 4-titanium valve cylinder head, as opposed to 2009's 5 valve layout. Bore, at 97.0mm, is larger, while stroke, at 60.8mm is shorter. Compression ratio was upped on the 2010 model to 12.5:1.

Reversing the exhaust and inlet locations means the airbox and fuel tank followed suit. The air cleaner box is now located where the tank was, so the intake tract can have a straight shot into the cylinder head (which improves intake efficiency). To achieve the proper exhaust pipe length from the rearward-slanting cylinder, the pipe twists in a distinctive tight coil before reaching the muffler, which is 150mm longer. Repositioning of the airbox means the bulk of the fuel tank now sits under the seat and between the frame rails in a more "vertical" configuration. This enhances the mass centralisation and reduces the impact on handling caused by variance in fuel loads.

From CDR's perspective, the all-new package meant a whole new set of challenges in developing another race-winning machine. When he spoke to JUST BIKES prior to the start of the 2010 Rockstar Energy Drink MX Nationals, CDR's head of Engine Development and Logistics, Shawn Hodgetts, acknowledged that the team had been working on development since the bike's September 2009 launch and that he and the rest of the team were confident they had a great race bike on their hands. Jay's result proves that! In his interview with JUST BIKES, three-time Australian MX Nationals champion Jay Marmont was effusive in his praise of the new YZ. According to Jay, the old carb bikes were like farm bikes compared to the new technology!

It isn't all about the engine, though. The 2010 YZ 450F's frame is also an entirely new bi-lateral beam aluminium design that's more symmetrical, another flow on from the redesigned engine package. 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 new semi solid die-casting technology High Solid Die Casting, which allows complex shapes to be made stronger, whilst also ensuring more consistency with other parts. The symmetry of the design means response around the steering head is more consistent, which in turn gives greater rider control and more predictable handling. The under-engine skid plate is a lightweight design in keeping with the rest of the frame.

Suspension is all new, too. Freeing up the airbox space means the re-engineered rear suspension could be moved forward into the space previously occupied by the airbox. The shock itself sits in line with the central axis of the frame, while the swingarm follows the frame design in being very symmetrical. Front forks have greater capacity and a 10mm longer stroke, which is tuned to ensure high traction under a variety of riding conditions.

In factory spec, the rear sprocket shape is a new shape, and the triple clamps are redesigned - with offset increased from 22mm to 25mm. Factory-fitted ProTaper bars feature four-way adjustment.
Given all the other changes, the redesigned plastics came in for the least attention when the 2010 YZ 450F was launched. What is interesting to note, however, is that less plastic is used, in order to expose and enhance the frame and componentry.

Adjusting engine mapping to suit different terrain, temperature and riding styles is made easier with an optional GYTR Power Tuner aftermarket accessory. This "plug and play" device makes changing the EFi settings and ignition mapping a breeze. At the launch for 2010 YZ 450F, Jay Marmont provided the assembled testers with some of his own personal settings, which most agreed made for a package that performed and handled flawlessly.

While CDR obviously fine tune and fettle their bikes, the factory-spec 2010 YZ 450F isn't really all that far removed from what Jay rode to win this year's championship. After developing a motocross winner, the challenge is for CDR to apply their expertise in turning the 2010 YZ 450F into a Supercross-winning machine as well. Given what they've achieved so far, we're pretty confident they can do it!

2010 YZ450F - Factory Specs.
Engine: 450cc liquid-cooled DOHC 4 valve 4 stroke single
Bore/Stroke: 97.0 x 60.8mm
Compression ratio: 12.5:1
Lubrication: Dry sump
Fuel System: Yamaha Fuel Injection
Ignition: TCI
Starting: Kick
Transmission: Constant-mesh 5 speed
Fuel Capacity: 6.0lt
Front Suspension: KYB telescopic fork - 310mm travel
Rear Suspension: Swingarm w/KYB single shock - 312mm travel
Front Brake: 250mm single disc
Rear Brake: 245mm single disc
Dimensions (LxWxH): 2194x825x1311mm
Seat height: 998mm
Wheelbase: 1487mm
Ground Clearance: 383mm
Wet Weight: 111.5kg

YZ Power Tuner FI setting tool accessory
The 'Power Tuner' was developed so riders can adjust fuel injection volume and ignition timing to meet personal taste or course conditions. The compact tool with liquid crystal display is small enough to fit in a pocket and has setting function and monitor functions.

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 Yamaha Motor Australia as an aftermarket accessory.

Marmont scores top ten, Aussies finish sixth at MXoN
Team Australia finished sixth overall at the 2010 Motocross of Nations (MXoN) held at Thunder Valley MX Park in Colorado, USA over the weekend of September 25-26. Brett Metcalfe was the standout rider for the three man Aussie squad, finishing third and fifth in his races. In his debut appearance, Jay Marmont scored solid 18-10 results. In the first Open-class moto, Jay was riding strong within the top ten when Team USA's Trey Canard collided with him on the final lap. Jay managed to remount and finish in 18th place. In the second Open moto, Jay fought his way from the middle of the pack to finish tenth. Fellow Australian MXoN debutante, Dean Ferris, finished 18th and 27th in his two races.

Source: JUST BIKES, November 2010, Issue #257