SCASTU 250 VX.
An innovative enduro motorcycle featuring a large ground clearance, long suspension travel, and a low seat. The key solution is a vertical adaptive intake with air intake near the handlebars.
Grade 9
Марганець, Нікопольский район, Дніпропетровська областьWhy Анна Лисенко created the SCASTU 250 VX.
I became interested in motorcycles from an early age, and at the age of 12 I started studying their design and specifications. Later, when I learned to ride a motorcycle myself and began planning the purchase of new equipment, I noticed a problem: most off-road motorcycles have a seat height of 850-900mm, which is uncomfortable for riders under 165 cm tall. Because of this, you can barely reach the ground with your feet, making it difficult to maintain balance when stopped and to control the motorcycle on uneven terrain. Simply lowering the suspension and reducing its preload is not a good solution, since it reduces handling and ground clearance, which leads to worse off-road capability. I put off thinking about this problem for a long time because there were fewer opportunities and less reason to deal with it; I hope that this competition will give me the chance to express myself and show what my project is capable of. SCASTU 250 VX (Smart Construction Adaptive intake System Terrain Utility Vertical intake X-over) is an attempt to create an off-road motorcycle that combines off-road capability, comfort, and ease of control. It is suitable for people of short stature without the need to sacrifice technical specifications.
«Real limits exist only until we dare to rethink the possible».
— Анна Лисенко
How the SCASTU 250 VX works.
My first decision was to move the tank under the seat and install an air-box in its place. Having encountered the problem of cylinder fill loss in horizontal intakes, I decided to use the Helmholtz effect for a vertical fuel intake system. When I began calculating the approximate length of the intake manifold, I saw that to ensure strong thrust the intake tract must be long, while to prevent the engine from choking and to allow free air supply, that same tract must be short. Using a fixed length won't work — the engine will either fail to run well at high RPMs, or lose thrust and suffer fuel-air mixture dropouts at low RPMs. I came up with the idea of using a movable manifold with variable length. Since I don't have the ability to draw it in a CAD system, I sketched various mechanical variants in a notebook — a rotary drum, a dual channel with a vacuum "butterfly" valve, telescopic tubes nested one inside another (like in a telescope). The best solution turned out to be a telescopic intake system with variable length, but it is constantly moving while the engine runs. This created a risk of unfiltered air and dust being drawn into the engine. To solve this problem, reinforced corrugated tubing must be used to flexibly connect the moving pipe to the airbox housing. The closest relatives are the Yamaha WR250F and Yamaha SEROW 250. SCASTU's differences: it combines a low 750 mm seat, a 250 mm travel, and 270 mm of clearance with an under-seat tank and a movable variable-length
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