Circa 1933 one-off Harley Davidson Over Head Valve 500cc, 30.50 cubic inch single cylinder racing engine.  This experimental engine is the predecessor of the Harley Davidson CAC 500cc Speedway single racers.  This engine is a virtual copy of the J.A. Prestwich, also known as J.A.P. Speedway 500cc, 4 stud racing engine manufactured in Tottenham, England from the teens to the 1960's.  The J.A.P. Speedway machines were beating all comers including Harley Speedway racers.  The Harley racing department decided it was time to even the score.  A brand new J.A.P. 4 stud Speedway machine was purchased by the Harley race department.  Their express purpose was to dismantle and reverse engineer the OHV J.A.P. engine to improve Harley's raing performance by incorporating some of the J.A.P. designs.

William Harley and Joe Petrali, scratch built this one-off Harley Speedway engine copying a J.A.P. single in the Harley race department.  William Harley told Petrali to discard the J.A.P. parts. but soon realized they could reuse the carburetor and magneto off the J.A.P. engine.  He asked Joe what became of the carb and mag?  Joe replied he threw them in the trash as instructed.  Harley told him to go retrieve them, which he did.  The original Amal racing carburetor and the Lucas racing magneto were found and installed on this Harley one-off racing engine.  They remain in use on it today.

The Harley Davidson engine turns over and has  good compression.  This is the original untouched engine as given to Joe Petrali by William Harley at the end of their project.  At the base of the cylinder, "EX 1320" is cast indicating it is an experimental item.  The brand name, "Harley Davidson"  is in bas relief on the rocker box cover similar to where the J.A.P. engine has J.A.P. in bas relief.  Other than "EX 1320" cast on the cylinder and "Harley Davidson" in bas relief on the cover, there are no VIN , line bore, or date code numbers.  The engine case castings are rough and crude where reinforced around the crankpin.  The compensating sprocket is on the sprocket shaft.  Use as a show engine or build a truly one of a kind Speedway racing machine.

Sold as is, where as, no warranties or guarantees expressed or implied.  Please e-mail or call             (805) 933-1557       with any questions you may have.   Weight and size are approximate.  Shipping, crating and collection costs may differ and are the responsibility of the buyer.