Motocross Action is the Moto-Bible. Yamaha has been the one on the cutting edge of this new four stroke technology since the 1997 yzf 400m. They have beat Honda at their own game. Honda's market research told them there was no market for a cutting edge, race worthy, state of the art, four stroke. Yamaha invested millions on a gamble. The entire motocross world couldn't wait to find fault with it. They hoped it would be unreliable and a joke. It turned out it was bullet-proof and a hit offering new technology borrowed from road racing. Motocross Action has said for the last five years that Yamaha has had a yz150f on the shelf awaiting the nod for production but production would be a million dollar decision when casting and forging engine cases and parts. Yamaha never pulled the trigger because they knew the stupid AMA would ban it because it has no class to race in. Motocross Action says the big 5 have sat back waiting for Honda to go first because they are the largest manufacturer and if they made a 150 first then the AMA could not ignore them and would be forced to make room for the new machine. Yamaha deserves a ton of credit for this gamble in new dirtbike technology but one engineer at Yamaha deserves all the credit for the yz400f, yz426f, yz250f, and supposedly the yz150f. He developed the the 400 and 250 on his own time. Japan didn't want to produce the bike. American Yamaha begged Yamaha of Japan to build the bike because they said that it would sell in America. It is a cinderella story. Read Motocross Action.......The Moto-Bible.