It was a big racing weekend and just about every major story involved Yamaha riders.

The big news of course was the announcement that Valentino Rossi, the 31-year-old defending and seven-time world MotoGP champion, is leaving Yamaha for Ducati. This is a dream pairing for fans of the popular Italian marque and sets up a most interesting 2011 MotoGP season.

Can Rossi defy the odds again, as he did when he moved to Yamaha, and win an eighth MotoGP title on a third brand? One thing is for certain, Rossi to Ducati is the best thing that’s happened to MotoGP in a long time. The focus on Rossi will be white hot next season and the rivalry between him and Lorenzo is likely to grow to even more epic proportions.

The Rossi move also creates more interest among American fans since promising MotoGP rookie Ben Spies will now be on the factory Yamaha squad and, based on his solid performances this season on a Yamaha satellite team, could become a genuine title contender next season.

Speaking of Spies, the Red Bull Indianapolis Grand Prix is coming up in about a week and a half and Spies knows the track intimately. He’s only raced there once (as a wildcard for Rizla Suzuki in 2008), but he’s tested at the track and outside of Laguna probably knows it better than any other MotoGP circuit. He’s not said much about it so far, but I’m sure he’s eyeing a podium at Indy.

It was a wild weekend at Virginia International Raceway this past weekend. The Daytona SportBike races were phenomenal with series leader Josh Herrin being taken out of Saturday’s race by Project 1 Atlanta Yamaha rider Clinton Seller in the first turn. Seller got in too hot and used Herrin as a berm. Bobby Fong went on to win his first AMA national in a thriller over Martin Cardenas and Danny Eslick. Herrin recovered from Saturday’s debacle with a solid victory on Sunday in another thriller over Rapp and Eslick. The bottom line is that Eslick leaves VIR with a 12-point lead over Herrin. Cardenas is still very much in the hunt as well, and with four races remaining the championship will go to one of those three riders.

You can be sure the conference calls coming into Cypress, California, (Yamaha’s U.S. headquarters) will be hot and heavy today. In addition to Seller’s possible championship-costing move on Herrin in Daytona SportBike, Ben Bostrom slammed into American SuperBike points leader Josh Hayes in Saturday’s race, very likely costing Hayes the victory. It could have been worse. Had Hayes gone down in the contact, the championship may very well have been decided… in Suzuki’s favor!

Yoshimura Suzuki’s Tommy Hayden went on to nip Bostrom at the line in a photo finish. Hayes survived to finish third.

Inside sources tell me that Hayes was livid after Saturday’s run in with Bostrom. Obviously the rumors that Bostrom was blocking Tommy Hayden to benefit Hayes at Mid-Ohio were not true. It appears to be every man for himself at Yamaha, even though it’s Hayes who is the one battling to give Yamaha its first American SuperBike title since 1991 when Thomas Stevens gave the company its one and only title.

Hayes channeled his anger and blitzed the field Sunday. He leaves VIR with an 11-point advantage over Hayden. It’s not the cushion he hoped to have going into the final rounds at New Jersey and Barber. The SuperBike championship is very likely to go down to the final race.

SpeedTV.com’s Chris Martin gives a very good summation of what happened at VIR (which he cleverly called Yamaha on Yamaha crime).

James Stewart made his highly anticipated return to the Lucas Oil AMA Pro Motocross Championship. Coming off a bad wrist injury that happened early in the Supercross season, Stewart looked good as the fastest rider in qualifying. He then ran second in the first moto before crashing and being passed by GP contender Clement Desalle of Belgium. While Ryan Dungey won the moto Desalle held off Stewart to take second. In the second moto Desalle surprised everyone taking the lead and holding off Dungey for over 20 minutes. Dungey eventually got around his part-time Belgium teammate to sweep the motos and take first overall. Dungey will likely wrap up the title in the next round in Southwick, Mass.

Meanwhile Stewart was running just outside the top ten when he mysteriously pulled out in the second moto. No word yet as to why he pulled out, but I could tell by watching his interview before the second moto that Stewart was not too positive about his chances. Some people are saying Stewart was not yet in shape, but based on his body language, I suspect the wrist is still hurting. It will be interesting to see if Stewart returns to race any of the final three outdoor nationals. If he doesn’t that may indicate that Stewart’s return from his injury may take longer than anyone had hoped.