4-stroke Junior

New from 2025 is the 4-Stroke Junior class. In this new class, it is possible to participate with three different 4-Stroke engines. One of these engines is the iconic RK1 Junior engine. One of the longest-running racing classes in the Netherlands, the RK1 Juniors, will also compete in 2026 at the NXT GP.

The popular Honda 390cc engine has also been approved for the 4-Stroke Junior class. Finally, it is also possible to participate with a Tillotson T4 Junior engine on an open chassis. The rapidly growing T4 classes ensure that many standalone engines are coming to the market. These engines can also be used in the 4-Stroke Junior class. Therefore, you do not have to race on a Tillotson T4 chassis, but you may also use a different type of chassis.

All three engines compete for one overall classification. Will you be the best 4-Stroke Junior of 2026?

Technical overview

Engine: RK1 Junior, Honda 390cc or Tillotson T4 Junior
Frame: Frame choice free, Senior-Frame.
Junior Age: 10 to 16 years old.
Tires Junior: Maxxis Sport (slicks) & Maxxis MW (rain tire)
Top speed: 100km per hour