Question: What type of transportation does John Boulger and Jack Young have in common?

Context paragraphs:
1951 Individual Speedway World Championship: Speedway riders from Sweden, Scotland and Republic of South Africa was started in World Championship first time.  Australia's Jack Young became the first British second division rider to win the World Championship.  Young won a run-off for the title with British rider Split Waterman and fellow Australian Jack Biggs after all three riders had finished on 12 points.

Crevalle jack: The crevalle jack, "Caranx hippos" (also known as the common jack, black-tailed trevally, couvalli jack, black cavalli, jack crevale and yellow cavalli) is a common species of large marine fish classified within the jack family, Carangidae.  The crevalle jack is distributed across the tropical and temperate waters of the Atlantic Ocean, ranging from Nova Scotia, Canada to Uruguay in the west Atlantic and Portugal to Angola in the east Atlantic, including the Mediterranean Sea.  It is distinguishable from similar species by its deep body, fin colouration and a host of more detailed anatomical features, including fin ray and lateral line scale counts.  It is one of the largest fish in the genus "Caranx", growing to a maximum known length of 124 cm and a weight of 32 kg, although is rare at lengths greater than 60 cm.  The crevalle jack inhabits both inshore and offshore waters to depths of around 350 m, predominantly over reefs, bays, lagoons and occasionally estuaries.  Young fish dispersed north by currents in the eastern Atlantic are known to migrate back to more tropical waters before the onset of winter; however, if the fish fail to migrate, mass mortalities occur as the temperature falls below the species' tolerance limits.

Bob Leverenz: Bob Leverenz (6 February 1925 – 16 March 2009) was an international speedway rider who featured in the 1951 Speedway World Championship final alongside the winner and fellow Adelaide rider Jack Young.

1952 Individual Speedway World Championship: Australian rider Jack Young became the first ever dual winner (and the first to win two in a row) when he won his second straight World Championship after scoring 14 points.  Second was Welshman Freddie Williams on 13 points, with Britain's Bob Oakley third on 12 points.

Ocular albinism type 1: Ocular albinism type 1 (OA1), also called Nettleship–Falls syndrome, is the most common type of ocular albinism, with a prevalence rate of 1:50,000.  It is an inheritable classical Mendelian type X-linked recessive disorder wherein the retinal pigment epithelium lacks pigment while hair and skin appear normal.  Since it is an X-linked disorder, it occurs mostly in males, while females are carriers unless they are homozygous.  About 60 missense and nonsense mutations, insertions, and deletions have been identified in "Oa1".  Mutations in OA1 have been linked to defective glycosylation and thus improper intracellular transportation.

Lewis Young: Lewis Jack Young (born 27 September 1989) is an English professional footballer who plays for Crawley Town.  He can play either as a striker, as a right winger or as, most recently, a right back.  He is the younger brother of Manchester United footballer Ashley Young.

John Boulger: John Boulger (born 18 June 1945 in Adelaide, South Australia) is a former international motorcycle speedway rider.  After he retired from riding Solos in the early 1980s, Boulger raced somewhat successfully in Speedcars (Midgets) from the mid-1980s until the mid-1990s.  Boulger won a record nine South Australian Championships (a record jointly held with 1951 and 1952 World Champion Jack Young) as well as two Australian Solo Championships during his career.

Jack Young (Australian rules footballer): Jack Young (14 August 1908 – 1 December 1979) was an Australian rules footballer who played with Carlton and Melbourne in the Victorian Football League (VFL).

Jack Young (speedway rider): Jack Ellis Young (31 January 1925 in Adelaide, South Australia – 28 August 1987 in Adelaide) was a Motorcycle speedway rider who won the Speedway World Championship in 1951 and 1952.  He also won the London Riders' Championship 1953 and 1954 and was a nine time South Australian Champion between 1948 and 1964.

East Dunbartonshire Independent Alliance: The East Dunbartonshire Independent Alliance was a minor political party operating in East Dunbartonshire, Scotland, represented on East Dunbartonshire Council until October 2012 by Jack Young, one of the three councillors for Kirkintilloch East & Twechar, and until July 2012 by Charles Kennedy, one of the three councillors for Campsie & Kirkintilloch North.

Supporting paragraphs: John Boulger Jack Young (speedway rider)
Answer: motorcycle