Honda stopped producing two-stroke motorcycles over ten years ago, and there are no indications of that changing in the near future. However, dedicated two-stroke enthusiasts like John Murray are taking matters into their own hands. Murray has taken the concept of two-stroke conversions to the next level with his “Under Construction” project, a Honda CRF450R powered by a KTM 300SX engine.
John Murray, a self-proclaimed “Honda guy,” is an avid dirt bike rider and tinkerer when he’s not running his family business. As a fan of both Honda and KTM, Murray had the idea to combine his love for Honda with a modern two-stroke engine platform. With a Honda CRF450R and a KTM 300SX in his garage, Murray set out to make this idea a reality.
After some rough measurements, Murray and his friends realized that the KTM engine could almost fit into the Honda frame. However, modifications were needed to reconfigure the intake system to accommodate the Honda’s downdraft design. They also had to make adjustments to clear the KTM’s two-stroke cases and ensure proper engine placement and drivetrain alignment. Despite the challenges, Murray’s vision was becoming a reality.
The conversion process involved minimal cutting and welding on the Honda CRF450R chassis. The main frame required some grinding, and new engine brackets and pipe mounts were created to fit the KTM engine onto the Honda frame. The coolant hose routing posed some challenges, but they found solutions without significant radiator modifications. The air-intake system utilized components from both the KTM and Honda, incorporating “real-world application techniques.”
The exhaust system required modifications to align with the cylinder’s exhaust port angle, ensuring clearance with the frame’s “Y” junction. Although the modified exhaust worked well, it is not a commercially available option from FMF. It is unlikely that we will start seeing KTM 300-powered Hondas everywhere because building a usable bike from two brand-new bikes can be quite expensive. However, Murray’s project showcases what can be achieved with determination and a vision in a garage.
Despite its rough appearance, Murray’s CR300 project delivered excellent performance during testing. Minor issues were quickly resolved, and the bike was a joy to ride. The only downside was having to return the bike after testing, as it was shipped far away. Murray’s project demonstrates the potential of a modern-day Honda two-stroke and highlights what can be accomplished by an average person with determination and a vision. Thank you, John!
