The buzz of motorcycle en gines was heard at the Naples Moto-Cross Track on Airport Road Sunday, as 92 entries took part in the day's activities. A crowd of about 500 looked on. Brian Cronin won first place honors in the mini-class while John Hacheley finished second. Both rode Yamahas. Senior mini-class trophies were awarded to Chuck Calkins, first place on a Yamaha; Tommy Exline, second place on a Honda; Mike Arick, third place on a Kawasaki; and Steve Shaffer, fourth on a Honda. The 100 cc class was won by Robert Boyette, who rode a Hodaka, while Steve Edwards, on a Yamaha, wound up second. Jeff Kasel rode a Suzuki to a third place finish, and Danny Walsh saddled his Yamaha to fourth. Rodney Earnshaw took top honors in the 125 cc category, riding a Suzuki. Billy Slisk took the second-place trophy on a Husquevanna. Third spot was filled by Mark Diefenthaler on a Kawasaki, and Don Taylor was fourth on a Maico. The fastest rider in the 200 cc division was John Rimes, who piloted his Kawasaki past runner-up Eddie O’Bannon, who mounted a Bul Taco. A Husquevarna ridden by Dennis Veechon was third, and Mike Sellers ended up fourth on a Suzuki. The 250 cc class saw John Zeims capture first on a Hon da. Gary Coke was second on a Yamaha, while Tom Hine was third on a Kawasaki and Roger Morris fourth on a Yamaha. Jeff Kasel engineered his Suzuki to a first place finish in the open class, while Mark McQuade, on a Husquevarna, was runner-up. Terry Schaffer, also on a Husquevarna, was third. A Yamaha ridden by Johnny Raulerson wound up in fourth place. A ‘‘slow race’’ was held at intermission, and was entered by all types of bikes. Danny Walsh was the winner on a Yamaha. This race illustrated riders’ skills in balance and control. Every first place winner in Sunday’s competition was, in addition to his trophy, awarded a $10 gift certificate from the Naples Honda Shop. The next race will be July 8 at the Naples Moto-Cross Track. This race will be the last of the summer pro-am series races. Prizes will be awarded for the ten race effort to teams throughout the state. All heats will be 15 minutes endurance events, with qualifying heats in the morn ing.