View source for AJS 7R

{{Use dmy dates|date=February 2018}}
{{Use British English|date=February 2018}}
{{Infobox Motorcycle
|name=AJS 7R
|image=AJS 7R motorcycle.jpg
|caption= AJS 7R in [[road racing]] configuration
|aka='Boy Racer'
|manufacturer=Associated Motor Cycles
|parent_company=
|production=Pre-war 1936 to 1939 (factory racing)<br>Post-war 1948 to 1954 (factory racing), 1954 up to 1963 (public availability)
|predecessor=
|successor=
|class=
|engine=348cc single SOHC four stroke
| bore_stroke = {{cvt|74|×|81|mm}}<br />{{cvt|75.5|×|78|mm}}
|wheelbase=
|length=
|width=
|height=
|seat height=
|power={{convert|37|bhp|abbr=on}} at 7500 rpm.
|torque=
|dry_weight={{convert|285|lb}}  
|fuel_capacity= 
|fuel_economy= 
|transmission= 
}}

The '''AJS 7R''' was a British 350&nbsp;cc racing [[motorcycle]] built from 1948 to 1963 by [[Associated Motor Cycles]].
It was also commonly known as the ‘Boy Racer’, and won victories both for the factory and for privateers right from its introduction in 1948.

==The AJS 7R==
A new design by Phil Walker, the chain-driven overhead camshaft 7R had the history of the pre-war AJS ‘cammy’ singles behind it. Initially, the 7R was not quite as powerful as its competitors, producing {{convert|32|bhp|abbr=on}} at 7500&nbsp;rpm. The duplex frame and Teledraulic front forks remained relatively unchanged during production, while the engine had a number of changes. The included valve angle was progressively narrowed, and the [[crankshaft]] strengthened. In 1956 the engine dimensions changed from the original long-stroke 74 x 81&nbsp;mm to the ‘squarer’ 75.5 x 78&nbsp;mm. The AMC [[gearbox]] replaced the older [[Burman and Sons Ltd|Burman]] unit in 1958.<ref>{{cite web |title=1959 AJS 7R |url=https://silodrome.com/1959-ajs-7r/ |website=Silodrome |accessdate=6 July 2018 |date=2 August 2017}}</ref>

==AJS 7R3==
In 1951 [[AJS]] development engineer Ike Hatch developed a 75.5&nbsp;mm bore x 78&nbsp;mm stroke, three valve head version of the 7R making {{convert|36|bhp|abbr=on}}. It was called the AJS 7R3, and was Ike's response to the Italian multi-cylinder racers. They did well enough in their first year, not as well the second. For 1954 Jack Williams, the works team manager, developed the bike further, lowering the engine in the frame, and making some tuning changes that gave {{convert|40|bhp|abbr=on}} @ 7800&nbsp;rpm. It immediately won the first two rounds of the World Championship and took first at the [[Isle of Man TT]]. These were factory specials, but one has survived, and a second has been reconstructed from spares.<ref>{{cite web|url=http://www.realclassic.co.uk/news030522.html |title=AJS 7R3 Racebike Revival |accessdate=2006-10-25 |url-status=dead |archiveurl=https://web.archive.org/web/20060908160419/http://www.realclassic.co.uk/news030522.html |archivedate=2006-09-08 |website=RealClassic}}</ref>

==Racing==
The 1957 AJS 7R 350&nbsp;cc, with 75.5&nbsp;mm bore and 78&nbsp;mm stroke, gave {{convert|38.5|bhp|abbr=on}} at 7600-7800&nbsp;rpm, and weighed 285&nbsp;lb (129&nbsp;kg). The top speed was 180-190&nbsp;km/h (115-120&nbsp;mph).<ref>{{cite web|url=http://www.southward.org.nz/viewgallery.php?id%3D4 |title=AJS 7R 1964 |accessdate=2006-11-04 |url-status=dead |archiveurl=https://web.archive.org/web/20061008133406/http://www.southward.org.nz/viewgallery.php?id=4 |archivedate=2006-10-08 |website=Southward Car Museum }}</ref>

AMC withdrew from the world of works, and one-off, road racing at the end of the 1954, with the death of Ike Hatch, and in the face of fierce competition from the other European bikes.

After this AJS made a production version of the standard two valve AJS 7R, for privateers and a 500&nbsp;cc version, badged as a [[Matchless G50]] was also sold. By the end of production in 1963 the two valve [[OHC]] AJS 7R engine made over {{convert|40|bhp|abbr=on}}.<ref>{{cite web|url=http://www.worksengineering.com/manifesto.html |title=A.J.S. 7R |accessdate=2006-11-04 |url-status=dead |archiveurl=https://web.archive.org/web/20070310133934/http://www.worksengineering.com/manifesto.html |archivedate=2007-03-10 |website=Works Engineering }}</ref>

Swedish rider [[Bill Nilsson]] converted an AJS 7R road racing machine into a [[motocross]] bike and rode it to win the inaugural [[Fédération Internationale de Motocyclisme|F.I.M.]] 500cc [[List of motocross World Championship results|Motocross World Championship]] held in 1957.<ref name="GODSPEED! BILL NILSSON (1932-2013)">{{cite web | url=http://motocrossactionmag.com/news/godspeed-bill-nilsson-1932-2013 | title=GODSPEED! BILL NILSSON (1932-2013) | publisher=motocrossactionmag.com | accessdate=2015-12-16 }}</ref> AJS 7Rs won the 1961, 62 and 63 Junior [[Manx Grand Prix]] [[road racing|races]] and came second in 1966.

==Sources==
{{reflist}}
==See also==
*[[List of motorcycles of the 1940s]]
*[[List of motorcycles of the 1950s]]
[[Category:AJS motorcycles|7R]]
[[Category:Motorcycles introduced in the 1940s]]