Setting Up For Super X

While the bikes that the CDR Rockstar Yamaha team campaign in motocross and supercross are the same machines, there are a number of fine adjustments that go into converting the Yamaha YZ 450F from a long track to a short track machine. Some of the changes aren't all that obvious, and at first glance may seem minor, but as Shawn told JUST BIKES, they played a big part in making Jay Marmont and their guest riders' bikes race-ready for Super X.

"The supercross format, with its much shorter distances between all the obstacles, turns and jumps means the engine power needs to be a lot 'snappier' and more immediately responsive to throttle input," Shawn explained.

"We achieve this by using different camshaft profiles and adjustments to the Vortex ignition module that all our bikes are fitted with. There are four separate settings on those modules that we adjust from track to track to change the power delivery. Things like the exhaust system remain constant between both types of competition, but we will do modifications to the airbox for supercross to allow more or less 'breathing' to suit the track conditions.

"Gearing is changed, too. Normally, we run a rear sprocket that's two or three teeth bigger than what we run for motocross. That gears the engine down to improve the power delivery for the supercross format - you need that 'snap on' power there quickly, because the tracks are so condensed, whereas with motocross, it's more overall speed that's needed, and at higher revs, too."

As reported in JUST BIKES' coverage of the Super X series, weather conditions have varied a lot between rounds, as well as the quality of soil used in the track composition. CDR fine tune the gearing from track to track by adjusting that rear sprocket - usually one tooth either way - to suit the track surface and conditions. It doesn't sound like much, but Shawn explains it makes a significant difference. As such, the front sprocket isn't adjusted, as it would make too big a difference.

"An extra tooth on the sprocket would equal three on the rear, so it's a major change", Shawn said.

"It's also not really necessary, as it's easier, quicker and more efficient to make those changes to the rear sprocket when you've got the back wheel out of the bike."

"The other main difference for supercross is in the suspension. To handle the big jumps and whoops that are part of all the Super X tracks, the suspension needs to be a lot firmer, so we adjust preload and rebound settings to make it a lot stiffer than what we use for motocross. We were lucky this year in that after the Motocross of Nations, myself, Gary Benn, Jay and Jay's mechanic, Jason Childs, spent three days at Yamaha's test track in California. We met up with Ross Maeda and Will Decker from Enzo Racing. We did a lot of suspension testing over there and those guys were awesome. They came up with some good stuff that helped us out. That gave us some valuable data ahead of the Super X series."

The addition of EFi to the YZ 450F has meant all the teams running Yamahas have had to learn a whole new skill set, the key to which lies in the Vortex ignition. While there are four separate adjustment screws on these modules, for supercross only two are subject to regular adjustment.

"The Vortex ignition module is adjustable four ways through the screws on top", Shawn explained.

"The first adjusts the ignition curve. Ten full and different ignition curves can be programmed into that module. The other three are dedicated to the fuel/air mixture - low range, medium range and high range. Normally for Super X, we only adjust the low and the medium-range mixture screws to change how the power is delivered at low and medium revs. If the rider wants the power delivery to be more aggressive, we can adjust it to suit that. But if the track's getting harder, for instance, we might adjust the low range screw to make the fuel/air mix richer and mellow out the power a bit. At the wet races, we ran a totally different ignition curve and low range mixture to make the bike a bit easier to ride in the tough conditions, but still with enough power to get through the mud, so it is a fine line in making those settings."

While Shawn, Gary Benn and the individual riders' mechanics, Jason Childs and Todd Woodcock, do all the initial settings, the final call lies with the rider. If Jay or, in the case of Super X this year, Jeff Alessi want to adjust the gearing or fuel/air mix in the Vortex ignition, then those changes are made at their request, and their requirements will vary from track to track.

Tyres are always important, and not just for Super X. This year CDR have been using the new Dunlop GEOMAX motocross tyres. These are available in three basic compounds, from the hardest 'MX71' spec, through the intermediate 'MX51' to the softest 'MX31', which is really a full-on sand tyre. Shawn explained that the tread pattern, compound and carcass construction varies a lot between each tyre. The MX71 hard tyre and MX31 are completely different in terms of the traction and 'feel' they give to the rider.

"At most of the motocross tracks this past year, we ran an MX51, and for supercross we would usually run an MX71, as the track surface is usually a lot more hard packed than a motocross track. But with the wide range of track and surface conditions in Super X this year, we used all three. In the mud-fest at Brisbane, the MX31 was the only choice, whereas at some of the other rounds, we were running a mixture of MX71 and MX51. A lot of this is the rider's choice.

"We do a fair bit of tyre testing and experienced riders like Jay know after a few sighting laps what sort of tyres they need to best suit the conditions, so that makes it easier. After viewing the track and doing some practise laps, the track might become more churned up or packed in. Then the rider will make a decision on what tyre they want to race with."

As the riders are on different soil every round, they'll pick a front and rear tyre combo to suit. And yes, the dirt does make a difference. To paraphrase a famous ad slogan, 'dirt ain't dirt'. From state to state, the dirt used to make the tracks is always different, Shawn told us, and as such, reacts differently.

"For example, the two mud races - Dunedin and Brisbane - looked similar, but they were very different sets of mud. At Dunedin, the track got put in 'hard', so it had a good firm base and was only slushy on top, whereas at Brisbane, it was mud all the way through. It got wet when they were dumping the dirt, wet while it was sitting (at the venue) and wet when they were building the track, so it made a lot of difference. But everyone's got to race on the same track, so we and the riders adapt to it as best we can. We ran the softest MX31 tyres at both those rounds.

"Even at the dry rounds, the tracks behave differently under the tyres, so after some practise laps, tyre changes are pretty common."

In the muddiest conditions, foam becomes a rider's best friend. You've probably seen riders with foam strips on their helmets that are designed to reduce mud build-up. The same goes for muddy supercross races. At the wet rounds, CDR ran handguards on their bikes to keep the rider's hands free of mud, so they could operate the throttle and levers better. In addition to this, carbon fibre sump guards were also used, and packed with foam between the guard and the engine.

"We put foam everywhere we can around the engine to keep the mud out. This isn't just to keep mud from potentially damaging components, but also to help keep the bike a bit lighter. A lot of mud caked on to everything really does add weight. We also run a different rear brake disc for the mud races. As it doesn't have holes, it keeps the mud out and helps the brake work better and for longer. We've got a choice of three different compounds for the rear brake pads, which the rider chooses based on what he feels comfortable with.

"On the front brake, we use those covers you've probably seen, but we always run a Braking 'Bat-fly' rotor with a grooved design that cleans the mud out from the rotor and pads, and that's the same rotor we use for motocross as well, regardless of the conditions."

Each CDR rider had specific setup requirements for Super X racing, too. Jay Marmont did a lot of clutch adjustment ahead of Super X, which Shawn felt improved his starts and early lap pace. Jay also had specific ignition settings that, like the clutch adjustment, were honed during testing in the USA.

Justin Brayton ran a lot of his own Joe Gibbs Racing (JGR) equipment, which was shipped out from the US, so CDR didn't have the same level of involvement with Justin's Super X preparation as they did with Jeff Alessi. Like CDR, JGR were running the all new YZ 450F for the 2010 season, and they shared similar experiences in developing the new bike. Time spent with CDR in the Super X series was valuable for both Justin and the JGR team ahead of the 2011 AMA Supercross series in the USA.

Jeff Alessi, CDR's guest rider for the last four Super X rounds, was riding Cheyne Boyd's former bike, so the team were already familiar with it.

"Jeff liked a 'mellower' power delivery setting to suit his riding style, so we adjusted the camshaft timing, Vortex ignition and even the Pro Circuit pipe to cater for that, so he didn't have as 'snappier' power as Jay", Shawn said.

"He ran different gearing, too. He liked the revs to be a lot lower. So with the taller gearing and mellower power delivery, he had a totally different set-up to what Jay was running. Jeff also prefers a lower seat height, so we had a special, lower gripper seat made up for him."

CDR are set to bring something new to the motocross paddock in 2011. Keep an eye on JUST BIKES for more details in future issues. Check out what's happening with the CDR Rockstar Yamaha team, find out more about their bikes, and purchase merchandise online at www.dackracing.tv