Question: Which year did Harley-Davidson finish first and third in the 250cc world championship? Water Villa and Franco Bonera were the riders.

Context articles: List of 250cc/Moto2 Motorcycle World Champions
Harley-Davidson
Hideo Kanaya
Alan Carter (motorcyclist)
Roberto Gallina
1962 Grand Prix motorcycle racing season
List of 125cc/Moto3 Motorcycle World Champions
Fumio Ito
Dario Ambrosini
Franco Bonera

Grand Prix motorcycle racing is the premier championship of motorcycle road racing, which has been divided into three classes since 1990: 125cc, 250cc and MotoGP.
 Former classes that have been discontinued include 350cc, 50cc/80cc and Sidecar.
 250cc is the intermediate category; the 250cc refers to the size of the engines of the motorcycles that race in that class.
 The engines have twin cylinders, as opposed to the four cylinders used in MotoGP.
 The Grand Prix Road-Racing World Championship was established in 1949 by the sport's governing body, the Fédération Internationale de Motocyclisme (FIM), and is the oldest motorsport World Championship.
 The 250cc class was replaced in 2010 by a new class called Moto2.
 The 250cc engines were replaced by 600cc engines, which were supplied by Honda to all teams.
Harley-Davidson, Inc. (H-D), or Harley, is an American motorcycle manufacturer, founded in Milwaukee, Wisconsin in 1903.
Hideo Kanaya (Shinjitai: 金谷 秀夫 , Hideo Kanaya , February 3, 1945 – December 19, 2013) was a Grand Prix motorcycle road racer from Japan.
 Kanaya began his Grand Prix career in 1967 and won his first Grand Prix at the 1972 250cc German Grand Prix.
 In 1972, Kanaya and Jarno Saarinen raced the first four-cylinder, two-stroke Yamaha TZ 500 in the 500cc world championship.
 After Saarinen's death in the 250cc race at the Italian Grand Prix at Monza, the TZ 500 project was put aside and Kanaya raced only in the 250cc class.
 Kanaya's best season was in 1975, when he finished third in the 500cc world championship behind his Yamaha team-mate, Giacomo Agostini and MV Agusta's Phil Read.
 He also won the Macau Grand Prix in 1975.
Alan Carter (born in Halifax 19 August 1964) is an English former Grand Prix motorcycle road racer.
 He competed from 1983 to 1990 in the Grand Prix world championship.
 Carter won the second Grand Prix race he entered, in the 250cc class at the 1983 250cc French Grand Prix as an eighteen-year-old, creating a sensation.
 However, he was never able to fulfill his potential and never won another Grand Prix.
 He had his best season in 1985 when he finished in seventh place in the 250cc world championship.
 Carter competed in the World Superbike Championship in 1994.
Roberto Gallina (born January 4, 1940 in La Spezia) is a former Italian Grand Prix motorcycle road racer and racing team owner.
 His best year was in 1973 when he finished eighth in the 250cc world championship.
 After his racing career ended, he started his own racing team which proved to be a successful venture.
 He won two 500cc world championships as a team owner in 1981 and 1982 with riders Marco Lucchinelli and Franco Uncini.
The 1962 Grand Prix motorcycle racing season was the 14th F.I.M. Road Racing World Championship Grand Prix season.
 The season consisted of eleven Grand Prix races in six classes: 500cc, 350cc, 250cc, 125cc, 50cc and Sidecars 500cc.
 It began on 6 May, with Spanish Grand Prix and ended with Argentine Grand Prix on 14 October.
 Defending 350cc and 500cc world champion Gary Hocking was deeply affected by the death of his friend, Tom Phillis at the 1962 Isle of Man TT and, announced his retirement from motorcycle racing after winning the 1962 Senior TT.
 Hocking's MV Agusta teammate, Mike Hailwood went on to win his first 500cc world championship.
Grand Prix motorcycle racing is the premier championship of motorcycle road racing, which is divided into three classes: Moto3, Moto2 and MotoGP.
 Former classes that have been discontinued include 350cc, 250cc, 125cc, 50cc/80cc and Sidecar.
 Moto3 replaced the 125cc class in 2012.
 Moto3 runs 250cc single-cylinder engines as opposed to the 125cc engines used previously.
 The engines have single cylinders, as opposed to the four cylinders used in MotoGP.
 Moto3 is the class where young riders first participate in Grand Prix motorcycle racing.
 The minimum age for a rider is 16 years and the maximum is 28 years.
 The Grand Prix Road-Racing World Championship was established in 1949 by the sport's governing body, the Fédération Internationale de Motocyclisme (FIM), and is the oldest motorsport World Championship.
Fumio Ito (10 October 1939 – 10 March 1991) was a Japanese professional Grand Prix motorcycle road racer.
 Ito began his Grand Prix career in 1960, although he was a Factory Yamaha rider as far back as 1957 where the Yamaha YD-A & YD-B 250cc machines were so devastating in the Asama highlands race, where Yamaha took the first 3 places with Matsuko on a YD-A taking the honors.
 Ito himself could have easily won the race and had set the fastest lap, but his YD-A motorcycle seized and cost him the race.
 The machines were later modified for the 1958 Catalina GP in States with smaller fuel tanks taken from the YA 125 machines, high pipes and high footpegs.
 Ito was the Star rider of the team and the only Japanese rider alongside four local American riders.
 Ito finished 6th, even after an unscheduled pit stop for a fouled plug.
 He enjoyed his best season in 1963 when he won the 250cc Belgian Grand Prix and finished the season in third place in the 250cc world championship, behind Jim Redman and Tarquinio Provini.
Dario Ambrosini (March 7, 1918 in Cesena - July 14, 1951 in Albi) was an Italian Grand Prix motorcycle road racer who competed for the Benelli factory racing team.
 He finished second to Bruno Ruffo in the inaugural FIM 250cc world championship in 1949.
 He returned in 1950 and claimed the 250cc world championship with three victories including one at the 1950 Isle of Man TT.
 Ambrosini was killed during official practice for the 1951 French Grand Prix at Albi.
Gianfranco Bonera (born April 2, 1945, in Porpetto, Province of Udine) is an Italian former Grand Prix motorcycle road racer.
 His best year was in 1974 when he won the Nations Grand Prix and finished second to his MV Agusta teammate, Phil Read, in the 500cc world championship.
 He switched to the 250cc class in 1976, racing for the Harley-Davidson factory racing team on Aermacchi machines rebadged after being purchased by the American firm.
 He won the 250cc Spanish Grand Prix and finished the season in third place behind his Harley-Davidson teammate, Walter Villa and Yamaha's Takazumi Katayama.