If you were following AMA Pro Roadracing in 2012-specifically the Daytona SportBike class for middleweight bikes-it was hard not to notice a particular Yamaha consistently at the front in the final half of the season. After fracturing his kneecap in three places-ouch-in a scooter accident at home following his impressive third-place finish in the season-opening Daytona 200 (forcing him out of three of the next four races on the AMA schedule), Cameron Beaubier mounted an impressive comeback that resulted in the northern Californian winning seven out of the final 11 races on the calendar. Unfortunately those missed races proved vital in the title chase, keeping Beaubier out of the championship picture despite his dominant close to the season.
With its incredibly tight restrictions on engine modifications, the Daytona SportBike class has been heralded as one of the more level playing fields in racing. It's supposedly a far cry from AMA 600 Supersport days of yesteryear when factory-supported teams did battle on bikes that were said to be light years from what a privateer could build. Thus, when Yamaha called and asked if we'd be interested in riding Beaubier's Yamaha Extended Service Graves Motorsports R6 at the newly constructed NOLA Motorsports Park just outside of New Orleans, Louisiana, my bags were packed before I had hung up the phone.
In order to keep an iron-fisted control over the competition, the rules for the AMA Pro Roadracing Daytona SportBike class are very strict. Internal engine modifications are basically limited to compression, cam timing, and fueling/ignition; everything else must remain in the completely stock form as homologated with AMA Pro Racing. No more cylinder head porting, special cams, valve jobs, etc. Spec fuel means that engine tuning opportunities revolving around secret petrol brews are out of the question.
As expected with such a tight rulebook, Y.E.S. Graves Yamaha team manager Rick Williams was decidedly tight-lipped about what engine modifications were made to the R6s ridden by Beaubier and teammate Tommy Hayden. "You change the compression ratio with the Y.E.C. head gaskets and that sort of thing, find the sweet spot, it's more tuning than anything," said Williams about the main power producer in the modification list. The rest goes into cam timing-"We use the Graves Motorsports camshaft timing kit, the same one we sell"-velocity stacks on the throttle bodies (another Graves component) and engine fueling/ignition via the Marelli SRT 16-bit ECU. Needless to say there is surely more handiwork performed inside the engine, but the Graves crew isn't talking. Exhaust is a Grave Motorsports full titanium system.
Clutch modifications are allowed as long as they are homologated products, so the Y.E.S. team fitted Beaubier's R6 with his preferred STM slipper clutch unit. The slip ratio of the STM clutch is highly adjustable, allowing tailoring to a particular rider's style. Graves WORKS rearsets, handlebars, and case covers ensure crash survival and positive control. Race bodywork is by longtime maker Sharkskinz, with Zero Gravity (a company with an even longer racing history) making the windscreen.
Graves WORKS adjustable rearsets...
Graves WORKS adjustable rearsets allow perfect foot placement, with a full titanium Graves exhaust system poking out below. Braking rear disc on near side, with Vortex CAT 5-520 sprocket and D.I.D. ERV3 racing O-ring chain on the other.
Even with the strict AMA rules,...
Even with the strict AMA rules, there’s still room for electronic trickery in the Daytona SportBike class. The grey toggle switch is for the engine braking maps, while the red toggle switch is the master power switch (the one on the right bar is the engine kill switch). Yellow button is the pit-lane speed limiter.
Ohlins TTX shock has valving...
Ohlins TTX shock has valving made to Graves specifications, with Graves’ own spring fitted. The Graves springs are lighter and offer half-steps in spring rates for optimum tuning capability.
Suspension is handled by Öhlins components that are made to Graves' specifications, with a TTX shock and fork cartridge kit (because AMA rules specify that the stock outer fork assemblies must be used) utilizing Graves-spec damping rates. Graves has its own springs manufactured that are lighter and less progressive than the stock Öhlins springs. The Graves springs are also made in half-step rates that allow finer adjustment than the Swedish springs, and the difference in spring length is minimal between spring rates. A Graves rear shock linkage changes the leverage ratio to a more optimum curve for racing, and a Graves top shock mount allows easy ride height adjustability.
Speaking of ride height adjustability, the problem with changing one aspect of the chassis is that it can affect many others, causing unwanted side effects. In order to counter this, Y.E.S. Graves suspension technician Kyle Guglielmetti showed me his "Dynamic Chassis Program" that basically takes the guesswork out of what a particular change will affect and where. Any alteration to ride height, spring rate, preload, damping, oil level, linkage-even gearing change (anti-squat characteristics) or tires (circumference)-is fed into the DCP spreadsheet, which instantly displays on a graph where the bike's dynamic center of gravity (as well as a few other important handling parameters) is located. The program can give you options on what should be changed elsewhere on the bike to keep the bike's dynamic center of gravity in the same spot in order to help maintain consistent handling, or choices to allow you to change it to a different location.
Brake rotors and pads front and rear are from Italian manufacturer Braking, with Vortex CAT 5-520 sprockets running a D.I.D. ERV3 racing O-ring chain. Internally, a Speedcell lithium battery helps provide electrical power with less weight, while Yamalube full synthetic 15W-30 motor oil provide power through light weight of a different kind. And finally, Dunlop's D211GP-A Sportmax DOT race rubber-the spec tire of the AMA Daytona SportBike class-put that power to the ground.
Despite the tight rules on modifications in the Daytona SportBike class, there's still a bit of electronic trickery available on the Y.E.S. Graves Yamaha R6. A toggle switch on the left clip-on bar offers two levels of engine braking, with another button for the pit-lane speed limiter. An electric quickshifter is also allowed in the class.
Rolling out of the NOLA circuit's pit lane for my first exploratory laps (learning a track and racebike at the same timenot the ideal scenario), I was surprised at how hospitable Beaubier's R6 was when not ridden in anger. Any expectations of an abrupt, snarling engine or concrete-stiff suspension were quickly dispelled in the first few turns; you could be forgiven for thinking that you were aboard a nicely set-up street-going sportbike if you were blindfolded. In fact, as my pace increased throughout the day, I found that the Y.E.S. Graves Yamaha never lost that friendly character.
Granted, this is a race-tuned 600cc four-cylinder engine we're riding, so keeping the revs up in the five-figure zone means you can't get lazy. You're rewarded for your work though, with an engine that is in another galaxy compared to the stock R6. Yes, there's plenty of screaming top-end power-although the team is loathe to quote horsepower numbers, my butt dyno put the Y.E.S. Graves R6 in the 125-130 rear-wheel horsepower range, with the engine making strong power all the way to 15,000 rpm with a nice overrev-but even more impressive is the surprisingly strong midrange. Letting the revs drop to 9000 rpm is no longer a death sentence to any sort of drive off the corner, and the smooth yet crisp throttle response means you can start those drives earlier and more aggressively.
Credit here goes to the Marelli SRT standalone ECU. As a point of reference, I also got the chance to spin some laps on Garrett Gerloff's Supersport-spec Y.E.S. Graves R6, a class that requires the stock ECU to be used (with a homologated piggyback fueling device). Engine regulations between the two classes are the same, however, so while the overall power felt basically the same, the way it came on when you twisted the throttle was definitely rougher and more abrupt.
Suspension action from the Graves-spec Öhlins suspension was superb, and despite the Y.E.S. crew's offerings of adjustments, I never saw the need (of course, much of that could be attributed to my outweighing Beaubier by some 30-odd pounds and going a lot slower). The NOLA track's new surface meant that there weren't many bumps to be found, but the few I was able to locate didn't upset the Y.E.S. Graves R6 in the least.