Patents on Rapide Engine?


New Forum User
Non-VOC Member
Vincent H.R.D. Club Members,

I'm currently writing a 2-part story for "The Antique Motorcycle" magazine (USA) about the Harley-Davidson high-cam KL model of the early 1950s. This bike was intended to match or exceed the performance of the best Brit bikes, but never made it out of the prototype stage. Instead riders got the lack-luster Model K/KH (with side-valve engine) in 1952-56 and later (1957) the XL model "Sportster," an overhead-valve machine still being produced today.

In my research on this high-cam KL model, its trail crosses that of the great Vincent Rapide V-twin in a couple of different ways. One is that the Milwaukee firm may have looked at the Rapide engine for inspiration when designing the high-cam KL motor, and I already stated that in Part 1 of the story.

But more critically there is an American published work called the "Harley-Davidson Data Book" (p. 87) where under "H-D Board Minutes" for 1953 the author claims that the KL motor was dropped due to "patent restrictions" with the Vincent motorcycle company.

While that reads like fact no one from Harley whom I interviewed mentioned any patent issue. That's not to say that a patent issue didn't possibly exist, but in searching I have not been able to find any reference to patents covering the Rapide-type engine. In addition, the "H-D Data Book" contains many mistakes, including several errors listed under "Board Minutes," so I'm suspicious that this might be another one. Thus I'm wondering if you Vincent experts can set the record straight on this patent issue.

Were there any patents issued that covered the Rapide-type high-cam engine held by Vincent or Phil Irving or anyone else that Harley-Davidson might have been afraid of? If there are such patents, can you direct me to an online source so I can examine them?

That Rapide engine was a stunner. Like many other times you Brits were ahead of us in the motorcycle game.

Thanks for your help,
Herbert Wagner

Ken Targett

Active Forum User
Non-VOC Member
Hello Herb.

I put together a list of Vincent patents a while ago, see below. You should be able to view the content of each by going to:
and the in the address bar changing the last bit to the Publication number of the patent you want.

By the way, as far as I am aware, PEI was never named as an inventor on any patents while he was with Vincent.


Ken Targett

Publn DatePub NoInventorApplicant/AssigneeTitle15/05/28GB290375PCVImprovements in or relating to spring frames for the driving wheels of cycles, motorcycles, and the like vehicles26/02/35GB424644PCV & VHRDCLImprovements in or relating to cycles, motor-cycles and the like provided with a passenger or luggage carrying platform02/11/36GB456025PCV & VHRDCLImprovements in or relating to wheel-carrying frame structures for cycles and other road vehicles14/11/38GB495568PCV, GAEC, WC & FEWImprovements in variable velocity ratio transmission gear22/07/41GB538132PCV & VHRDCLImprovements in multiple grip vices or jigs10/09/43GB555869PCV & VHRDCLImprovements in or relating to control mechanism for clutches15/09/43GB555974PCV & VHRDCLImprovements in or relating to charge feeding devices for internal-combustion engines25/04/44US2347444PCVVHRDCLCompressor for internal combustion engines13/03/45CA426146PCVVHRDCLCOMPRESSOR FOR INTERNAL COMBUSTION ENGINES15/09/43GB555975PCV & VHRDCLImprovements in or relating to motorcycles19/06/44GB562124PCV & VHRDCLImprovements in or relating to cooling means for the pistons of internal-combustion engines26/02/45GB567646PCV & VHRDCLImprovements in or relating to transmissions for motor vehicles09/06/47GB588971PCV & VHRDCLImprovements in or relating to driving units for motor vehicles07/10/47GB593069PCV & VHRDCLImprovements in or relating to driving units for motor vehicles01/04/52US2591219PCVVHRDCLDriving unit for motor vehicles30/09/52US2612148PCVVHRDCLDriving unit for motor vehicles05/10/49FR950728VHRDCLPerfectionnements aux ou se rapportant aux ensembles de traction pour véhicules à moteur21/11/49FR952611VHRDCLPerfectionnements aux blocs de traction pour véhicules automobiles29/08/50CA467774PCVVHRDCLDRIVING UNITS FOR MOTOR VEHICLES16/01/51CA470942PCVVHRDCLDRIVING UNITS FOR MOTOR VEHICLES03/03/49GB619046PCV & VHRDCLImprovements in or relating to clutches, brakes and like friction couplings24/02/53US2629473PCVVHRDCLFriction clutch10/05/49CA456619PCVVHRDCLCLUTCH, BRAKE AND LIKE FRICTION COUPLING28/08/57GB781946PCV & VE(S)LImprovements in or relating to internal combustion engines04/08/60GB843441PCV & VE(S)LImprovements in or relating to automatically engageable and disengageable clutches04/08/60GB843633PCV & VE(S)LImprovements in or relating to power transmissions for the propeller shafts of boats26/04/67GB1066881PCVImprovements in or relating to internal combustion engines26/04/67GB1066882PCVImprovements in or relating to internal combustion engines25/02/70GB1182250PCVVRELImprovements in or relating to Rotary Internal Combustion Engines.27/08/68US3398727PCVVRELRotary internal combustion engines29/03/71SE333840PCVVREL06/08/70DE1601334PCVVRELUmlaufender Verbrennungsmotor15/02/71CH503193PCVVRELVerbrennungsmotor mit umlaufenden Zylindern22/01/75GB1380941PCVINTERNAL COMBUSTION ENGINES30/10/73IT958919PCVMOTORE A COMBUSTIONE INTERNA07/12/72DE2224666PCV05/01/73FR2138815PCV15/03/74FR2196433PCV20/10/75IT994606PCVMOTORE A COMBUSTIONE INTERNA28/11/74JP49124407PCV14/10/75US3911874PCVPCVInternal combustion engines28/02/74DE2341487PCVPCVVERBRENNUNGSKRAFTMASCHINE