Bike Dissected: Luke Styke’s 2013 Yamaha YZ250F

After narrowly missing out on the championship last year, Serco Yamaha hoped this bike would serve as Luke Styke’s redemption. The 22-year-old has just clinched the 2013 Monster Energy MX Nationals MX2 title with one round to spare at Toowoomba, August 25 – meaning that this might be the last carb-fed four-stroke to ever win a national in Australia; maybe even the world! The following article was published in Transmoto‘s August Issue (#34), when the 2013 series had just reached its halfway point…

Serco has been around the MX traps since just after the turn of the century; which is a grand way of saying they’ve a decade’s worth of experience in the Pro Lites class. In partnership with Yamaha, they’ve produced some fine bikes and outstanding riders, and season 2013 sees them in with a great chance of taking out the championship with their No.1 rider, Luke Styke. The 22-year-old from Jervis Bay (NSW) nearly performed this feat last year, leading the championship from the second round, only to be dealt a bad hand and coming up two points short of taking out the title in his first full season with the Serco Yamaha concern. Although Styke’s been in Yamaha’s MX system for numerous years (having already won the Under 19 title back in ’09), 2012 was meant to be a learning year for the young charger, rather than one where he challenged for the title all year long. He was aided in his quest by the then fresh-for-2012 YZ250F, which debuted a new frame and various engine mods. That bike became the basis of the 2013 race bike, and the latest weapon relies heavily on data found from Serco’s previous campaigns. With more off-season testing on a ‘dyno mule’ YZ-F, Luke’s race bike has been built to offer power, rideability and the goal of domination in the Aussie scene. The result is the very bike that graces the next few pages, a machine that Serco hopes will propel Luke to the Pro Lites championship come season’s end.

Suspension

Modification, rather than replacement is where the 250’s suspension is at. The forks get slightly firmer spring rates (up .01 to .45) and the legs are treated to a DLC coating to improve their smoothness. In-house re-valving adds to this plushness and also increases the bottoming resistance when the 75kg Styke is in attack mode. At the rear, the standard shock retains its stock spring and linkages, settling for just a re-valve that helps in the aim of offering a plusher initial feel, increased bottoming resistance and better rear wheel drive over bumps.

Fuelling

Resisting the urge to jump on the fuel injection bandwagon (for now), the YZ250F’s Keihin FCR MX39 carb sees a series of modifications that start at the bike’s airbox. Extra holes are cut out of the plastic’s sides, allowing more airflow through the No Toil filter to reach the mechanical unit, which now runs an R&D fuel bowl and modified jetting to suit the changes to head and camshafts. The carb’s jetting only gets changed through the season when the bike is run in cool conditions – think an early Melbourne morning in August.

Brakes

It’s back to the future as the 2013 rear disc gets chucked in favour of a 2005 item. The team prefers the thickness and shape (round, not waved) of the older disc, as the feedback from the riders attests. The front disc gets a rework, too, with a GYTR oversized disc getting the call. At 270mm, it gains 20mm over the stocker. Standard lines, master and slave cylinders remain, as do the
brake pads themselves, though the rear pedal is replaced by a SPP item and a brake snake keeps it under control in the event of a collision.

Testing

A separate dyno bike is used for the numerous runs that any engine modifications require, and only when there’s proven results do those changes find their way onto the race bikes. Luke Styke and his teammate, Luke Clout, each have two bikes to cover the season. Their first race bike competes in the initial five rounds, before being swapped out for the final five. Which means that this won’t be the actual bike that Luke (Styke, not Clout) either wins or loses the championship on. Got it?

Standard Rules

For all the gold on this bike, it’s pretty obvious that most of the standard machine’s items are fit for the task of high-level racing. The wheels (from hubs to spokes to rims) are both stock, as
are the majority of the suspension components and all the bodywork. There are no fancy brake lines, no aftermarket footpegs and many of the items normally junked on a top-level race bike remain true blue. With these items of a known quality, it leaves more time for Serco to focus on the bike’s performance rather than the longevity.

Engine

A Vertex piston relegates the standard hole-plugger to the bin, but gets curbed itself after three rounds. The head gets modified with porting, the addition of a pair of Hot Cams and slightly firmer valve springs to suit. This helps deliver more power to the mid- and top-end rev-range. The bottom-end remains standard, except for the addition of a complete Hinson clutch assembly. The exhaust duties are trusted to Yoshimura’s RS-4 full system, feature a titanium header pipe with alloy muffler and carbon fibre end-cap.

Cockpit

After testing with a few different bends at the start of the season, Styke went with what he knew and stuck to the Carmichael bend Pro-Tapers, set neutrally in the same firm’s triple clamps. The bars are finished with Pro’s grips, which sit inside of the standard clutch and brake levers. Under Luke, a Factory FX gripper seat cover spreads over the bike’s original uncut seat foam and butts up (pardon the pun) to the stocker’s 6.4l fuel tank. Standard footpegs are more than enough to handle the action.

Michael Marty On Luke Styke

It’s been a fantastic start to the season for Styke and he’s picked-up where he left off in 2012. After the disappointment of losing out in last year’s championship by two points, I was wondering how long it would take for him to move on. However, he acted like a professional and used that lesson to make him stronger for this year. We’re expecting him to win the championship this year for us, as last year was more of a learning season. His results have impressed us all, and we know that if we keep him happy he’ll perform at the highest level. Our riders are on a year-on-year contract basis, and I know that Luke wants to use this time to propel himself into the motocross scene in Europe. With his focus and impressive training regime, I can see that happening.”

Luke Styke On Serco Yamaha

Before the call up to Serco, I was a privateer running under the radar. Up to then, no other team seemed interested. The change from sorting it all out myself, to having a well-organised team allowing me to just concentrate on riding and training, was immense. I’d been on Yamahas before, so jumping onto the Serco bike (set-up for the injured Jake Moss) was like coming home. I adjusted the levers and that was about it. After narrowly missing out on the championship last year, I’m expected to (and expect to) win it this year. So far, all my hard work is paying off, and having a fast and reliable bike helps me no end. I’m not stressed at the moment and I’m just looking at each race as another step to take. I arrive at races knowing that I’m the favourite and can beat everyone there. My confidence is high, but nothing’s won until the championship is wrapped up. I’ll be disappointed if I’m not riding in Europe this time next year.”

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Want to view this article in magazine form? Grab yourself a print or digital edition of Transmoto Issue 34.