4-stroke Senior

New from 2025 is the 4-Stroke Senior class. In this new class, it is possible to participate with five different 4-Stroke engines. One of these engines is the iconic RK1 Junior engine. We notice that the RK1 Junior engine is still widely used, especially by riders older than 16 years. This means participation in the 4-Stroke Junior class is no longer possible. However, it is possible to participate in the 4-Stroke Senior class with this same engine. The RK1 Bigbore engine is also allowed in this class.

The popular Honda 390cc engine has also been approved for the 4-Stroke Senior class. This widely used Honda engine is also frequently used in the 4-Stroke Senior class. It is also possible to participate with the Honda 9HP Senior.

Finally, it is also possible to participate with a Tillotson T4 Senior engine on an open chassis. The rapidly growing T4 classes ensure that many loose engines are coming to the market. These engines can also be used in the 4-Stroke Senior class. Therefore, you do not have to ride on a Tillotson T4 chassis, but you may also use a different type of chassis.

All five engines compete for one overall classification. Who will be the best 4-Stroke Senior rider of 2026?

Technical overview

Engine: RK1 Junior, RK1 Bigbore, Honda 390cc, Honda 9HP Senior, Tillotson T4 Senior
Frame: Frame choice free, senior frame.
Age: From 14 years old
Tires: Maxxis Sport (slicks) & Maxxis MW (rain tire)
Top speed: 100km per hour