The dirt track or speedway that was used for motorbike racing in Britain began in the late 1920s. This prompted many motorbikes manufacturers who existed then to jump on the bandwagon and design bikes that they considered could win races. Before introducing the Excelsior JAP speedway series in the market, Douglas and Rudge were the talks of the town for a long time in Britain. Excelsior’s first Speedway JAP that came from their pipeline was released in 1930 and began to take over from Douglas and Rudge. That period of dominance that started in 1930 was prolonged until the 1960s. It was a period of pure fun and excitement that the fans can remember to date. This article is a remembrance of the 1949 Excelsior JAP Speedway that was part of that fun creation.
The 1949 Excelsior JAP Speedway was released after the first models of the Excelsior generation to the market in 1949. According to FichasMotor, this speed motorbike encompasses models that have different displacements from a motorcycle generation that has lasted over 73 years. The JAP engine was a proprietary engine made available for all manufacturers who needed an engine for their bikes. Specialist frame developers could design their bikes and then fix the JAP engine. Excelsior was establishing his company and during that time was a JAP customer. He retained his speedway model even after the conclusion of WW2. This master-class motorbike that took dominance in speedways competition was taken to Wembley Stadium when Australia was playing with England in a test match in 1949, the year it was released in the market. It came with a complete program, steel shoes, and a helmet. The first models to be released were sold for $2,924. According to Bikez, this Excelsior piece of art is described by vendors across the world as a ‘100% correct quality restoration model which has a 1949 four stud JAP engine. For vintage motorbike lovers who love to collect every information about these types of motorbike, this bike was featured in the Classic Bike Magazine in 1989 in their February edition. It was owned by Alford of Southampton, who had several speedway bikes collections. There are a few brands that people own across the globe. If you find an original bike anywhere that hasn’t been restored, it will have an original rear rim of 22 inches. Restoration has been done for this bike to fix the damaged parts when the motorbike took part in races. The areas that spoil most are the frame, forks, and engine parts. This bike is among the first lightweight motorbikes used in motor races, and features a short 4 JAP stud.
Engine and Transmission
The 1949 Excelsior Speedway has an engine displacement of 497.00 CCs, meaning it does not consume a lot of fuel. This bike operates with a single-cylinder engine type with 2-stroke. The bike uses only two strokes to operate and reach the maximum speed limit. The bike will make a complete power cycle when the two-piston strikes. They work in such a way that: The intake in the engine and compression processes will complete when the first stroke of the piston is complete. The second stroke at the piston helps to complete the exhaust and power process. When the 1949 Excelsior JAP Speedway is ignited and begins to move, the thermal efficiency of the stroke engine of this bike will depend on the bike design. When the two strokes continue to make complete bike cycles, the engine of the bike will convert 20% of the fuel in the spokes into mechanical power. About 15% of the available energy is what the bikes will use to propel the two wheels. The remaining 5% of energy is lost in various actions such as resisting friction when the bike is speeding. These two-stroke engines work best with this motorbike because it is light.
This speedway bike uses an Amal twin float carburetor intake system, which works by atomizing the required amount of fuel with air that the bike draws in the engine parts. When the engine is engaged, it will open the idle throttle from its position. When the throttle is open, it increases the air intake in the mixing chambers. As a result, the needle valve will start opening up. When this happens, it will increase fuel consumption proportionally. If you don’t know how to tune the “Amal twin carbs,” you need to adjust the tick above the idle. This is just it on a somewhat fast idle, and it will help you know when to stop stalling the engine and ensure that you use the fast idle and not in a faster way.
The Excelsior JAP speedway 1949 uses an overhead valve fuel control system. These valves work best in engines that have valves situated in the cylinder head that is found above the combustion chamber. It is different from the bike with flathead engines. The camshaft helps in fuel control in this system by moving the valves through the tappet, rocker arms, and pushrods to ensure that the air-fuel mix in the engine of this bike is appropriately mixed and spread across evenly to the combustion chambers.
Chassis, Suspension, and Wheels
The front and rear brakes used are the expanding types of brake drums. This type of break will expand when the bike rider applies the brakes for a long time until it begins to generate heat. This happens when braking is challenging, especially in emergency cases to avoid high-speed accidents. The brake shoes need to be moved farther outward when they expand to function well.
This bike comes with a single seat. Therefore, it is not for carrying passengers as it is mainly used for competition purposes.
The 1949 Excelsior JAP Speedway is a factory-produced rear bike. The memory created back in the 50s will always be remembered for its part in motorbike competitions and bringing happiness and memory to millions of motorbike competition fans. The remaining models are preserved in various places as memorabilia by vintage enthusiasts.