The Whizzer motorbike most people are familiar with originated in 1946, with the introduction of the "H" engine. There was before that a "D", "E", and "F" engine, but they were not the same configuration as the later engines. The pot metal crankcase was made in two pieces, as were most of the motorcycle crankcases of the day, and was rather fragile. The metal has a tendency to rot, and fall to pieces. The "D" and "E" model engines turned clockwise, and drove the rear wheel through a friction roller mounted under the frame. They developed about 1 3/8 horsepower.

There was never an "A","B","C",or a "G" or "I" model, nor a "400" series, or at least they were never marketed.

A nice "D" model  The lever on the left side of the tank is the clutch. It is connected via a cable to the roller mechanism. Pushing the clutch forward makes the bike go. According to Leon Dixon, curator of the National Bicycle History Archive of America, the serial number of this engine is D003. As such, it may well be the earliest surviving Whizzer.

The "E" Model Whizzer   A nice view of the drive arrangement and clutch.     

The "F" Model came out during the War, around 1942.There were about 4250 of these, but probably not all were sold. The engine turned counterclockwise, and a belt drive to a rear sheave was used. It developed 2 1/2 horsepower. The gas tank more closely resembled the later tanks, except with a screw- on cap. After the war, Whizzer offered a substantial trade in for the earlier engines on the new "H" engine.

The "H" engine came out in March, 1946. It has a low fin head with the spark plug leaning towards the left side. The serial numbers run from H 501 thru H 140 000. (139,000 engines) The gas tank is plain silver/gray with a yellow decal on each side, and the compression release and throttle control are two thumb controls mounted on the right handlebar. The clutch lever is on the left handlebar. The carburetor is a Tillotson ML-5B. The valves are 3/4 inch in diameter. The crankcase holds 6 oz. of oil. The engine develops a whopping 2.5 horsepower.

The "J" engine was introduced in May of 1948. The external appearance is similar to the "H", except that the carburetor in most cases is a Carter "N". The tank is embossed WHIZZER on both sides, and the controls are motorcycle type twist grips. The serial numbers run J200,000 up to J252 +++, about 52, 000 engines more or less a few. There is an additional fin (5) on the cylinder at the valve body, and the fins on the cylinder are slightly larger. The intake manifold appears somewhat shorter and larger than on the "H", although that may be due to the larger fins. The valves are also 3/4 inch in diameter. The "J" also holds 6 oz of oil and is a 2.5 hp engine.

The "300" engine came out in November 1949. The head is a high fin, high compression head with the spark plug slightly to the right of center. The valves are 7/8 inch in diameter and the exhaust ports are larger than on the "H" and "J" . The cylinder block is also heavier in the area of the valves than on the "H". The Horsepower is up from 2.5hp to 3hp. The carburetor is either a Carter "N" or possibly a Tillotson MT- 12A on the later ones. The tank is embossed, and the controls consist of a trigger for the compression release and a twist grip for the throttle. The oil breather was made an inch taller than the "H" or "J", and the oil capacity increased from 6oz to 8oz. There is a "300***S" version with a kick- starter, introduced on the "Sportsman", and a "600***S" kick start which was introduced in 1951 on the "Ambassador"The kick- start engines are equipped with a generator built in to the side cover for lights and ignition. They do not use a magneto. The coil mounts on the right rear of the engine, in place of the points cover.

The "700" engine came out in 1952. It represents the last of the production. It is similar to the 300, except that it has a generator built into the side cover rather than having a magneto ignition. The carburetor is a Tillotson MT 12A. The "500" followed. It is basically a "700" engine, but without the side- cover generator. The "500" is not mentioned in any of the parts manuals.

The "500", "600S", and "700" engines had additional crankcase reinforcement added to the magneto coil mounting area, to prevent the mounting posts from breaking off, and the "300xxxS" and "600xxxS" engines had a kick- starter. Practically all of the engine parts are interchangeable, and that makes for some strange combinations. There were about 50,000 combined 300, 300S, 500, 600S, and 700 engines made, and if you add the 139,000 "H"s and 50,000 "J" s, a grand total of about 250,000 Whizzers. ..There is a surprising number of them left.

In 1992 there was an attempt made to market a reproduction Whizzer. The engine was re-designed around a Kohler K91 crank, rod, and piston. The engine and cylinder were of high silicon aluminum, and cast as a one- piece assembly. The gas tank is fiberglass, and resembles the embossed metal tank used on the "J" and later. Although it developed more horesepower than the originals, the engineering was not thorough enough, and the engine developed a horrible reputation for bad workmanship and poor dependability. The attempt was short- lived and not very successful. The engine, being cast in one piece, is relatively easy to spot.

The Whizzer name, logo, and patent rights were again bought out and an entirely different company has produced the latest Whizzer, beginning in 1998.It features a completely re-designed engine using modern motorcycle technology. The 26 inch bike has a purpose- built cantilever frame with a telescoping oil- shock fork, and except for the fork and the narrower fenders, somewhat resembles a WZ. The engine internals are massive in construction, and the design and workmanship appear to be excellent. The cylinder is cast aluminum, but with a steel liner and stellite valve seats. Outwardly,the cylinder resembles the "J" or "300".(five fins) The valves are large, nearly an inch in diameter. The crank is roller- bearing and the rod is a one piece forging, in keeping with modern motorcycle engine construction practices. The cam runs on ball bearings on both ends. There is a built- in alternator behind the flywheel which provides electricity both for lighting and for the capacitive- discharge ignition system, which is mounted on the lower toptubes of the bike. The New Whizzer Motorbike Company

It is not your "Old Whizzer" however, and the internal parts are not interchangeable with the original engines.

Whizzer introduced a new bike in April of 2000. It is a 24 inch version called the "Sportsman 24". The same frame is used as on the 26 inch, but with 24 inch wheels and fenders. Why they called it the "Sportsman" I have no idea, as it more closely resembles the Pacemakers.

June, 2001...Whizzer just announced the "PACEMAKER II" on their website.The New Whizzer Website The displacement has been increased to 148cc, with a corresponding increase in horsepower. The new Pacemaker is equipped with an automatic clutch, as well as an external band, drum type rear brake. It is available in both 24 inch and 26 inch sizes. The color is Maroon, and the tank logo more closely resembles that of the original "J" series.

The total count at this time seems to be around 7000 units of all types.

In 2005, Whizzer came out with the NE5 model. The cylinder has now been changed significantly, providing better cooling, especially in the valve area. I am told the valve seats are now poured into the casting instead of being pressed in, eliminating the problem of loose valve seats. The engine should be as "bomb proof" as anything ever made.