Shinichiro Yokoyama was often a confidant for
Warren and Matiasevich.

There is a period in Kawasaki's All-Japan Motocross racing history where the Lime Green banner was carried by American riders. From 1992 through 1994, that rider was Eddie Warren. He was followed by Jeff Matiasevich in 1995 through 1997. Between the two of them, they won four championships during their six-year tenure. The return to winning ways and a strong presence at the track is looked back on with pride.
"It had been quite a while since Atsushi Okabe's '89 Championship. It was time for a win and we needed something to get us fired up saying ‘This year we're going to take the title!'"
Shinichiro Yokoyama (motocross design team member at the time) explains the thinking behind the new team structure.
"In addition to winning championships, we had other objectives in mind when we appointed the Western riders. Even back then we used to say that racing was the testing ground for production model development. With the help of the American riders, whose pace was faster than the Japanese riders', we would be able to raise our development to a higher level. And not only machine development would benefit – by stirring up the Japanese motocross scene we would be able to raise the level of the series as a whole. That was our ideal outcome. In order to achieve it we couldn't simply hire the top American riders – there would be too much of a gap between them and the Japanese riders. It would be pointless for them to run away and win everything. We needed riders who could win, but who would have to fight for their victories – someone the Japanese riders felt was within reach. Choosing the right rider for the task was quite difficult."
The credentials of the first rider selected, Eddie Warren, included winning the 1985 AMA Supercross 125 East Championship and experience working as a test rider for KMC (Kawasaki Motors Corp., U.S.A.). And he had even come to Japan to compete in the 1991 Pan-Pacific Supercross held in Fukuoka.

Takashi Kono was KRT Team Manager
from 1993 to 2001.

Takashi Kono reminisces about working as Warren's mechanic in 1992 before taking over as KRT (Kawasaki Racing Team) Team Manager in 1993…
"Warren was the ideal candidate. He's a smaller rider, so couldn't rely on power to muscle the bike around, and because other riders could hang with his pace he was a perfect model for Japanese riders to emulate. His techniques were especially in evidence in the second moto of the day, when the course was really torn up. He would ride a gear higher than normal to keep engine rpm down, which let him ride more smoothly over bumps and ruts. Okabe used to study Warren's riding and picked up quite a few techniques."
In his first year in Japan, Warren rode his KX250SR to victory 10 times out of 24 motos, capturing Kawasaki's first title in three years.
"The season turned out just as we had hoped. Although that's not to say that as a mechanic I wasn't conflicted at times. Of course I wanted Warren to win, but I also had to bring along Shigeki Hanada (a rider for KRT at the time) and the other young riders. After fixing Warren's settings, I would advise Hanada's mechanic. We had some really great results, like the second moto of round 2 in Kyushu, where Warren, Okabe and Hanada finished 1-2-3. But although we had an American rider, on a personal level I always hoped that a Japanese rider would win. Even when Matiasevich joined the team, that feeling did not change."

The year after Warren's championship-winning season, Kawasaki contested the All-Japan Motocross series with a new KX250SR featuring an aluminium perimeter frame.

For the 1993 season, using Warren's development feedback, Kawasaki introduced a racer with an aluminium frame.
"While we usually develop our factory machines as predecessors to production models, the '93 KX250SR with its aluminium frame was an exception. We had tried numerous sand-cast parts and were able to accumulate a lot of data. The aluminium frame offered a lot of merit from a weight perspective, but at the time it was expensive to make so we decided to forego using it on our production models. Aluminium has both positive and negative characteristics. Reducing its inherent stiffness was difficult, but the experience we gained was very helpful years later when designing the aluminium frames used on the '06 model KX250F and KX450F."

In 1993, the title went to Suzuki's dark horse, Ron Tichenor. After conceding the title a second time in 1994, Kawasaki decided that it was time to bring in Warren's successor.
"We also considered Michael Craig and John Dowd, but in the end we chose Matiasevich. Having won the AMA Supercross 125 West Championship in '88 and '89, his supercross credentials were similar to Warren's, but his outdoor results were not as impressive. We wanted him to be able to beat Tichenor, but not by too large a margin. Matiasevich looked like he would be a good match. Unlike Warren, who had lived in Kawasaki's company housing in Akashi, Matiasevich commuted from the States for most of his races, but he still took the championship every year from '95 to '97."

Matiasevich was champion all three years he raced
in All-Japan Motocross.

The two Americans had completely different personalities. Kono, who was with them through both good times and bad, is still deeply impressed by their professionalism.
"After a race, both Warren and Matiasevich would be so out of breath, shoulders heaving, that they wouldn't be able to speak for a while. The Japanese riders, on the other hand, would be relatively composed, and as soon as their helmets were off, they would start debriefing their mechanics or rush off to give teammates lining up for the next race tips on course conditions. The Japanese riders didn't push themselves to the limit, whereas it was painfully obvious that the American riders, who would ride to the point where they would almost collapse, had a very different attitude when it came to racing. Everyone probably assumes that it was only natural for an American to win in All-Japan competition, but I don't think they realise just how seriously these riders took their work. Warren, who usually conducted himself with decorum, would be so frustrated after a loss that he would throw his helmet away in disgust once inside his trailer. Matiasevich would dump his 2nd place trophies in the trash. Not the most diplomatic behaviour, but it shows how much they wanted to win."
The era of American riders in Japan came to an end after six years. KRT's objectives – victory, development and breathing new life into the motocross scene – had been achieved. From that point on, the responsibility of ensuring a bright future for All-Japan Motocross would rest on the shoulders of young Japanese riders.