James "Bubba" Stewart's patience is being put to the test. But the 19-year-old motocross star still feels as if he knows the answers.

When Stewart takes to the track today at Budds Creek Motocross Park in the AMA Championship Series, he will do so in the 250cc division, having left behind this year the 125cc division he dominated after turning pro at 16. Now, on a larger, more powerful bike, he is among a more talented and seasoned cast of riders.

Winning, which came with staggering regularity in the 125s, hasn't come nearly as easily for Stewart. After winning three supercross races, which are run indoors, Stewart has yet to take a checkered flag in the 12-race outdoor motocross series in his first three starts.

"I don't think I've ever been challenged like this," said Stewart, who won his first amateur title at age 7. "I just want to go out and have fun, but I feel like I'm not having the fun I used to have."

Stewart turned pro in 2002 after winning 11 AMA amateur national championships and passing Ricky Carmichael as motocross's most successful amateur rider. Now Stewart is again chasing Carmichael, who has won the first three events of the series and is seeking his sixth straight AMA 250 championship.

"He just puts himself in a position to win," Stewart said.

It's not that Stewart feels out of place riding with the big boys, however.

"You have to know you're the best; the biggest challenge is mental," Stewart said after practicing in Southern California on Wednesday. "But I feel like I'm getting better. It's really a matter of time before I'm my normal self."

In the 125cc circuit, the entry level of professional motocross and supercross racing, Stewart became the most successful rider in the circuit's history. He broke the record of 14 victories in a season and became the youngest rider to win a supercross race and a motocross championship.

He achieved his success with an aggressive style, attacking corners, riding with abandon.

"He has a lot more style than the other guys," said Tucker Hibbert, a fellow 250 rider. "He moves around on the bike a lot and pushes the edge; he does a lot of things that other riders don't and can't do. He uses his body movement on the bike to do what he wants to do. On jumps, he's able to use his body to carry more speed."

The fact that he is black in a sport long dominated by white riders has only fueled his rise to stardom.

Said Andrew Lourake, operations manager for Budds Creek: "James has brought a whole new demographic to our sport, to our industry, by him being the first African American to win a championship in motocross.

"He's bringing a whole new dimension to what has been a white sport."

But when it comes to achieving the level of dominance he did at 125, Stewart is practicing patience -- with no small amount of difficulty.

"My mentality is that I will have my time," Stewart said. "My time will come for sure."

James "Bubba" Stewart, 19, who ruled motocross's lower division, will seek his first 250cc win this weekend in St. Mary's County.