The Wiseco Two-Stroke World Championship presented by Fasthouse at Glen Helen Raceway in Southern California has grown into a destination event for a huge amount of the two-stroke faithful crowd, almost like a yearly pilgrimage. In 2023, the Dirt Bike Magazine staff was fortunate enough to be a part of the first-ever “Live Feed” on YouTube in bringing a professionally filmed event to the world. Carson Brown was the Open Pro winner on a Yamaha YZ300 built by Twisted Development and backed by Fasthouse. For the 2024 event, Carson had a few different two-stroke project bikes to choose from. After multiple days of testing, Carson made the final decision to race a Suzuki RM300. Yes, you read that correctly.
Debbi Tamietti caught Carson Brown on the gas during moto one.
THE BUILD
You are also correct in thinking that Suzuki hasn’t produced a competition two-stroke motorcycle in almost two decades now, and the last time we asked, they said they had no plans in firing up production. Twisted Development decided to show Suzuki’s engineers what a modern-day RM two-stroke should be, and then let defending Two-Stroke World champion and Dirt Bike Magazine test rider Carson Brown showed the world exactly what it can do. We first laid eyes on this Twisted Development creation at last year’s event. The project had just been completed, but without the opportunity for major testing, the machine was not raced in the Premier class and was put on the back-burner.
This build started because Twisted Development frontman Jamie Ellis is a mad scientist and is always thinking outside the box trying to create something new. Twisted Development is a big part of multiple factory Suzuki-supported professional teams in recent years with riders like Ken Roczen, Shane McElrath and the entire BarX Suzuki 250cc effort. These teams also have facilities within walking distance of Twisted Development’s SoCal location, so as you can imagine, rolling RM-Z chassis are readily available for test fitting of different two-stroke engine platforms. Come to find out, due to the frame changes that Suzuki made back around 2017, the last-generation KTM 300SX carbureted engine fits into the current Suzuki RM-Z250 four-stroke chassis really well with some repositioning of engine mounts, of course.
Okay, we might be making that sound a lot easier than it actually is. But, unlike other manufacturers that people are retrofitting two-stroke engines into the RM-Z conversion, the 300SX doesn’t require fabrication of an entirely new lower engine cradle that moves the Y-section in order for the two-stroke exhaust to fit. As you can see from the images, completely new front and lower engine mounts were fabricated, and an upper head-stay mounting bracket was also custom-fabricated. The most important measurement or angle to correctly calculate is that of the countershaft and swingarm pivot; if this is not done correctly, the entire build is destined for failure.
With all the frame modifications complete, it was time to bolt in the KTM 300SX engine. Now, remember this is not your average stock 300cc engine. The crew at Twisted Development went all out on this one, getting every last ounce of horsepower available. We were not able to share actual dyno numbers, but let’s just say they are well into the built 450cc four-stroke realm.
Mitch Payton from Pro Circuit (PC) even got into the action on this build, authorizing the production of a custom exhaust system that featured some modifications to an existing PC Works-style expansion chamber and the first-ever PC Ti-2 Shorty that resembles their four-stroke-style exhaust canisters. Craig Monte from SDI dialed in a set of A-Kit suspension that was borrowed from one of the factory teams. Carson went to work customizing the RM300 with his personal sponsors like MotoSport, Devol Racing, Maxima, Renthal, Dunlop, Guts Racing, Kelly Farms and BBR Motorsports. Jared Hicks and the crew at Backyard Designs USA topped the build off with a completely custom chrome graphics kit that really made the bike pop.
CARSON’S THOUGHTS
“The smoothest and most consistent 300cc engine for me has been KTM’s carbureted 300SX, especially after Jamie from Twisted Development worked his magic on it! That paired with one of the bestknown handling chassis (Suzuki’s RM-Z), it ended up being an amazing combination. The bike had a good base for us to start with for how little time we had to get ready for the race. I had so much fun slicing and dicing around Glen Helen racing this bike. The best part is that the bike still has tons of room for improvement in the future.”
The Twisted Development KTM 300SX puts out some impressive horsepower numbers, and everything is available to the public.
THE FINAL WORD
The industry needs companies like Twisted Development pushing the limitations of what is possible. Unfortunately, the RM300 project doesn’t have that fairy-tale ending with Carson Brown dominating both motos of the 2024 Two-Stroke World Championship and riding off into the sunset, but it was close.
If it wasn’t for a flawless ride by Justin Hoeft on his Twisted Development-built and Fasthouse-backed YZ300 in moto two, the fairy tale would have been complete. If given the opportunity, Carson Brown would definitely be on board with giving the RM300 another shot at winning the Two-Stroke World Championship, and that is a very likely possibility in the future.
We are fortunate enough to work with Jamie and the entire crew at Twisted Development on a regular basis. As a matter of fact, we have just taken delivery of the only 2024 GasGas 150SX fuel-injected bike in the world built by them, so stay tuned for more info on it!
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