This year, American Motocross celebrates its 40th Anniversary, and the 12-race MX season begins with the Rockstar Energy Hangtown National and ends at Pala Raceway Sept. 10.In the 450 Class, Rockstar Makita Suzuki is the reigning champion. In this year’s Supercross season, Dungey finished third behind Two-Two Motorsports Honda rider Chad Reed and the 2011 SX Champion, Ryan Villopoto on the Monster Energy Kawasaki KX450F.On a sour note in Motocross, Team San Manuel Yamaha’s James Stewart is not starting this weekend, and it’s unknown if the team will compete throughout 2011. Muscle Milk/Toyota/JGRMX Yamaha’s Justin Brayton will also miss the opening round due to an injury.Following are some MX Sports team stats as the AMA Motocross heads into Hangtown:Rockstar/Makita Suzuki MotocrossThe reigning champion Factory Suzuki effort will feature the two fastest 450 Class riders from the 2010 season. Dungey returns to defend his crown after the most successful rookie season of all time.After a strong AMA Supercross effort earlier this year, he will look to give his team its third consecutive Lucas Oil AMA Pro Motocross Championship title. Joining Dungey under the Suzuki tent for 2011 is Australian Brett Metcalfe. Much like his teammate, Metcalfe experienced a tremendous rookie 450 Class season in 2010, finishing runner-up in the standings. The opportunity is Metcalfe’s best chance to win to this point in his career and he’ll look to break through for that elusive inaugural victory.Ryan Dungey says: “We’ve had a couple good weeks of testing. With 24 motos and 12 rounds, there’s a lot of racing, and it’ll be real exciting with a lot of good competition. I’m really looking forward to the outdoors. Hangtown is a great track. It’s always fun and real challenging. We’re going to try to get off to a good start and carry that momentum throughout the season.”Brett Metcalfe says: “We’re geared up and ready for Hangtown this weekend. I’m really looking forward to the outdoor motocross season. I’m feeling really fit and healthy. I can’t wait to get out there Saturday on the Rockstar/Makita Suzuki. I had a great season last year and I think I can definitely do it. There’s a lot of great competition – I think the field is going to be stacked and there’s going to be incredible battles all season long and I think the man who’s strongest and most consistent will pull off the championship.”Red Bull KTM MotocrossThe Austrian-based KTM team is putting its best foot forward for 2011. After bringing in legendary team manager Roger DeCoster to oversee the race team, KTM proceeded to sign perennial front-runner Andrew Short to join current rider Mike Alessi. Short has seen some success as he continues to acclimate himself to the new surroundings and he hopes to replicate his third-place championship finish from last season. As for Alessi, he hopes to kick off 2011 in a similar manner to the way he started 2010, by landing on the overall podium in Hangtown.Andrew Short says: “I have enjoyed the two-week break but am looking forward to starting the motocross season on the 350 SX-F,. It’s always exciting to show up at the first race. I can’t wait for the first gate to drop.”Mike Alessi says: “I am switching to the 450 SX-F for the outdoor series and I am looking forward to hopefully continuing my holeshots and leading some motos. I have high expectations for this season and hope that I meet my goals at the first round.”American Honda MotocrossThe American Honda team will start the 2011 season without either of its riders – Trey Canard and Josh Grant. Both riders are recovering from injuries suffered during the AMA Supercross season and will return to action in just a couple of rounds.In their place, veteran rider and fan favorite Kevin Windham will reprise his role as a fill-in rider. Last season, Windham made his long-awaited return to the Lucas Oil AMA Pro Motocross Championship for the second half of the season and experienced tremendous success, highlighted by a win at Steel City. While the length of his motocross season is still to be determined, Windham will surely enjoy himself while he’s around.Kevin Windham says: “I’m excited to race Hangtown. I had a great time racing those few races with the American Honda Racing team last season, so I’m happy I have the opportunity to race a couple more races with the team again this year. It’s a bummer that Trey and Josh are not racing the first few of rounds, however, I will do my best to fill in for them. I took the win last year at Steel City so let’s see what I can do this weekend.”Monster Energy Kawasaki MotocrossLast year was hard for the Monster Energy Kawasaki team, who ultimately suffered the loss of both of their riders by the completion of the 2010 season. Now, the team is back in full force, ready to reclaim the title they held in 2008.Newly-crowned AMA Supercross Champion Ryan Villopoto leads the way, looking to complete his first full season in the 450 Class. The former three-time 250 Class champion has never lost a title in motocross when racing for an entire year and strangely enough, Saturday will mark just his third career start in the premier class.Joining Villopoto as the new face at Kawasaki is Jake Weimer. The former 250 Class winner hasn’t had the opportunity to compete much during his rookie 450 Class season, but he will surely be up to speed with his counterparts quickly.TwoTwo Motorsports/Bel-Ray Racing MotocrossSo far in 2011, Chad Reed’s foray into team ownership has been extremely successful. After entering the year as an underdog, Reed is now a top contender and will receive the support of American Honda throughout the Lucas Oil AMA Pro Motocross Championship. As the defending race winner at Hangtown, Reed will look to start the year off right and keep his team’s impressive debut season going strong.Muscle Milk/Toyota/JGR Motocross The Joe Gibbs Racing effort boasts a strong rider lineup for 2011. Both Davi Millsaps and Justin Brayton have shown they can win at the elite level and have both experienced moderate success in motocross. After respectable AMA Supercross seasons for each rider, they are looking forward to finding their way to the front this summer.MotoConcepts Yamaha Motocross The up-and-coming MotoConcepts team made arguably the biggest move in the industry heading into the summer after signing French rider Christophe Pourcel. The two-time 250 Class runner-up chose to sit out the AMA Supercross season, placing an emphasis of achieving success in motocross. Many have awaited his move into the 450 Class since he came to the U.S. full time in 2009, and it would be no surprise to anyone if he’s challenging for wins almost immediately. Additionally, MotoConcepts boasts another pair of strong riders in Tommy Hahn and Kyle Chisholm, both of whom will look to build on their past success.Television coverage for Saturday’s Rockstar Energy Hangtown National begins with the debut of live coverage of the opening motos for both the 450 and 250 classes on FUEL TV, beginning at 4 p.m. EDT. Final moto coverage of the 450 Class will air at 11 a.m. EST on SPEED on Sunday, May 22, immediately followed by Moto 2 of the 250 Class at 12 noon EDT.