2023 KTM 250 SX-F Yoshimura RS-12 Titanium Exhaust | Track Tested

Yoshimura RS-12 Titanium Exhaust System

Price: $1299

Application: Tested here on 2023 KTM 350 SX-F

Yoshimura is a name that has been synonymous with four-stroke performance, long before the motocross and off-road world went valve-and-cam. With a rich heritage of high-performance road racing exhaust systems and engine packages, it was a given that Yosh would become a player when four-strokes began to dominate the dirt markets. As always, brands that are most associated together are heavily influenced by racing relationships and as such; most motocross riders first think of the factory Suzuki and factory Honda HRC teams when Yoshimura is mentioned.

And that’s a shame!

Many years ago, we first spotted a Yoshimura exhaust on a KTM 450 SX-F that was fielded by Yuta Ikegaya in the All Japan MX Championship. We thought it was odd seeing an Austrian motorcycle with a Japanese exhaust being raced in the Japanese MX Nationals but took a mental note that Yoshimura was now an option for KTM riders. Fun fact: although the company’s main headquarters is in Japan, all of Yoshimura’s off-road systems have been designed and produced in the United States at Yoshimura R&D of America.  

But enough backstory, already! We stopped by Yoshimura R&D of America’s headquarters in Chino, California, a few weeks ago to pick up a mountain bike stem (that’s right, Yoshimura has thrown its hat into the MTB arena with two industry-leading products), and were asked if we’d also like to test a new RS-12 Titanium system for the 2023 KTM 250 or 350 SX-F. The system was developed originally for the 250, but Yosh engineers discovered that on the dynamometer, it also yielded great results on the 350.

Our first day with the Yoshimura RS-12 system was at Perris Raceway, a tight, jump-laden course that the quick-handling nature and snappy powerband of the 350 SX-F feel great at. After riding a baseline moto with the stock system installed, we switched the exhaust in the pits. The RS-12 is a beautiful piece of work and everything about it – from the beautiful welds to the smooth matte finish of the titanium to the gorgeous carbon fiber end cap – seems too nice to be installed on a dirt bike. Everything fit nicely, and we appreciated that a high-quality spring puller is included with the system, too.

Photo by Twenty-Three Media

When we first took delivery of our 2023 KTM 350 SX-F, Tom Moen at KTM quipped, “I think you’ll have a hard time finding an exhaust that out-performs stock. The R&D team really put a lot of effort into the exhaust systems on all the bikes this year.” And initially, we believed him. Prior to the Yoshimura RS-12 system, we had tried another system but had eventually returned to stock because it gained in one place but only at the sacrifice of power elsewhere.

The Yoshimura RS-12 system on the KTM 350 SX-F, however, is downright shocking. The stock system produces a nice punch down low but suffers from a small flat spot before the mid-range power really kicks in. Well, the RS-12 fills that gap and produces low-end throttle response that simply blows the stock system away. While the low-end and mid-range power is improved considerably, though, that’s not the most impressive gain that the Yoshimura system provides. While the stock exhaust allows the 350’s engine to pull pretty far up top, the bike does taper off rather abruptly, but the RS-12 provides an eye-widening overrev that is hard to believe gained without ignition mapping or engine work. 

Photo by Twenty-Three Media

Since our initial track day at Perris, we’ve tested the RS-12-equipped 350 SX-F at Glen Helen Raceway and Cahuilla Creek Motocross – both much larger and faster courses than Perris Raceway – and were equally impressed with the performance of the system. In the past, we’ve been reluctant to race the open Vet class at Glen Helen aboard the 350 SX-F because we’ve been gobbled up on the long start straight leading into the Talladega first turn, but we’re confident that with the added top-end pull, getting a great start should be no problem. 

Every test rider who has thrown a leg over our KTM 350 SX-F with the Yoshimura RS12 system installed has come away very impressed. In fact, one 350 owner who asked to take a spin on our bike to feel what the enzo racing KYB conversion fork felt like, came off the track and asked what was done to our engine, as it out-performed his that was equipped with a different exhaust and a Vortex ignition. Simply put, the Yoshimura RS-12produces the biggest gains we’ve felt out of an aftermarket four-stroke in years, if not ever. Yes, it’s that impressive. 

Now, to find out how well it works on the 250 SX-F: the bike it was intended for!

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