Features and performance of the racing motorbikes


There is no brake


It is the largest feature of the racing motorbike. This is because an arbitrary operation of a brake may lead to a collision, since the race involves a physically close battle. In addition, the engine brake is strong, as the carburetor has no function of idling and the shutter thus shuts completely.


There are no measuring gauge


Everything that is unnecessary for the race is removed, such as the indicators of every kind and lamps. The engine will be started by pushing, as there is neither a starter nor a starting kick pedal.


Unique mechanism of suspension


The front is a telescopic fork with only the coil springs, and the rear is a total rigid type. This mechanism is designed to facilitate the controlling of the machine even in the case where the tires skid beyond their limit.


Heights of the left and right hand grips are different


The racing motorbikes run the course in a counterclockwise direction and are inclined throughout the race. For this reason, the left hand grip is higher so as to allow the stability when inclined.


Diamond-shaped frame


A diamond-shaped frame developed from the JAP excelsior type is adopted. The triangle frame, engine, engine plate and upper and lower back frames are all connected by bolts and nuts. The structure minimizes the deformation at the time of starting of the engine and falling. It is equipped with the accessories such as front and rear fenders, fender stay, saddle, knee pads, steps and chain case.


Two-speed transmission


Once you have started with a low gear and changed into the top gear, you will be required to accelerate and/or slow down using merely the accelerator. The utmost caution is required to exercise the control technique, as the power band of the top gear is extremely wide—as wide as 50km to 150km per hour.


Triangular tires


Both the front and the rear wheels are the tires of Dunlop, the KR-73, 3.00-20-4PR. In order to allow a better grounding in curves, the cross section of the tires is in a triangular shape. As the new tires are still not good enough in grounding, the surface of the tread on the grounding side will be scraped with a sander before using, and a “bedding” will be implemented by running the course for a few laps. The life of a tire is normally 3 to 4 races. There are no special tires for rainy days. The tires with a high tread are used on “rainy days” and those with a lower tread are used on “fair days”. In cold weather, the KR-73W tires may be used in the front/rear, which has an enhanced rubber pyrogenicity by changing the rate of the chemical composition.