Speedway Workshop

Today in Motorcycle History

The "Porkchop" Speedway Machine

(Pictures and Information Courtesy of Mike Heath in America).

Mike Heath kindly sent me this interesting information on the "Pork Chop" (also called the "Half Hog") of what was a Harley Sportster with one cylinder removed. I think Rick Woods tried riding it, to make up for weight and technology they ran a lot of nitro! This Hog was a Pig.

Here Rick Woods is about to give this "Half a Hog" a shakedown ride. Division three rider Denis Porter, co-builder of this sectioned Sportster, gave it a heat win at Costa Mesa April, 18th 1975. Picture was from Cycle News.

Not such a strange machine after all, as Ben Ludolphy has managed to come up with yet another "Half Harley" machine (Pictured Below). Here is some information and a photo from a machine that was built and owned by Johnny Griffits who hails from Riverside in California. Seems Johnny put this one together back in 1991.

Not sure what model Harley this one originates from, maybe someone looking in can put us right on that score. Housed in what appears to be normal JAWA type frame... please note the extra spark plug in the head.

According to Johnny, "the Half Harley lacks a little in horsepower, but has a heart the size of our nation".

Another well known contributor to these Pages is Bryan Lambert who is able to shed some light on these Harley's. Bryan writes:
This HD is an ambitious piece of work , the two machines differ considerably in detail. It is clearly based on a cast-iron Sportster , could be an XR, but the crank-cases and timing cases are cut down to remove the gearbox and generator, and reposition the cylinder (the first one still has the front pot in the V-twin attitude)

Both machines are modified to accommodate a conventional countershaft instead of the Harley gearbox. The twin-plug is a common racing mod on dragsters, the magneto is the usual Fairbanks-Morse fitted to racing HD engines which gives a 'dead' spark (ie on the exhaust stroke ) so both plugs spark on both strokes - so both leads can be fitted to either plug if required.

The rocker box has been cut in half, I don't know why but this is a common mod on tuned Sportsters. The chrome cylinder behind the engine will be the oiltank for the recirculating system whilst the carb is a Japanese Mikuni, usually a 38mm on Sportsters so once again, I would date this machine to the early to mid 70s

I like the euphemism about lacking horsepower ! the cast-iron XRs were terrible old dogs , HD were caught flat-footed by the AMA allowing in ohv 750cc engines and produced them as a stop-gap while the alloy XR was rushed into readiness . Apart from anything else they are petrol motors so the port shapes are wrong for dope and they were far too fragile for US-style flat-track.

Well, well - these Harley "Halfster's" seem to be generating an awful amount of interest and debate. Tony Manx kindly wrote in with a few opinions of his own regarding the pictures above. Tony writes:

The middle picture engine is a 1957 to 1970 type XL Sportster. This engine retained the FRONT cylinder in its original position. The rear cylinder was deleted. It uses an S&S carburettor (made in USA).

The lower pic was made from a 1957 to 1970 model XL Sportster. This is opposite of the pic above it. It retained the REAR cylinder, while the front cyl was done away with. It is not likely based on an XR, as they used roller bearing camshafts, with the magneto mounted in front of the engine where the generator would be on a street bike.
That pic has the mag in the position between the cylinders, as XL models were. Also, XL models used cams turning in bushings, and nothing interchanges in the timing chest between XL and XR models. An XR would also have been far to valuable to cut apart for a project like this. Unless it had been badly blown up.

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