Petrali and his modified Harley-Davidson and which stood at . The bike had to be in Los Angeles California before September 1948. 1B/900 was a factory-built racer, but as there was no plan to market such a version as a separate model when it was built, the bike began life as a Black Shadow even though it was later referred to as a Black Lightning by the factory. Vincent mechanic Cliff Brown writes that he built a modified engine for the bike, with extensive porting and polishing and a compression ratio of 12.75:1. Brown also reports that he designed and ground three sets of prototype MkII cams for the bike. This origin of the engine is disputed by Denis Minett, head of the Special Engine Department at Vincent at the time. 1B/900 was test-ridden by Cliff's brother George, who was said to have taken the bike to over at the Gransden Aerodrome. After this the bike was shipped to Vincent dealer V.L. Margin in California. Edgar had arranged for American Rollie Free to pilot the bike on the record attempts. Free unofficially broke the record during a test run at Rosamond Dry Lake in California with a recorded speed of 138 mph. On 13 September 1948 Free and 1B/900 appeared at the Bonneville Salt Flats in Utah, USA. On his first run Free set a new record for naturally aspirated motorcycles of . Free then stripped off his racing leathers and on his final run, lying prone on the fender of the bike, set a record speed of . A picture taken during this run earned this motorcycle the name "the bathing suit bike". On the basis of this run Vincent's subsequent advertising used the slogan "The world's fastest standard motorcycle: This is a FACT – NOT a Slogan!" Montlhéry 1952 With support from the Wakefield Oil Company, owners of the Castrol brand, Vincent took seven bikes to Montlhéry France in 1952 to challenge a variety of endurance records, the 100 mph for 24 hours record in particular. The bikes were a mix of Black Shadows and Black Lightnings, along with Gunga Din which served as a test hack and did not participate in the record runs. The Black Shadows that did run were modified to very nearly the same specifications as the Black Lightnings. The record attempts started on 13 May 1952 and continued for three days. The motorcycles