Yoshimura · RS-4
The Yoshimura SOUND INSERT KIT 99db RS-4 Muffler, 1.625" (INS-10-K) is a replacement low-volume insert kit designed for Yoshimura RS-4 mufflers. It’s intended for riders who need a different sound restriction option on supported applications, with decibel reduction varying by application.
This kit is listed for Honda CRF450R 2009–2010, Husqvarna Norden-901 2022–2023, KTM 350EXC-F 2011–2015, KTM 350SX-F 2011–2012, KTM 790-ADVENTURE 2019–2020, KTM 890-ADVENTURE 2021–2023, Suzuki RM-Z250 2010–2014, Suzuki RM-Z450 2008–2014, Suzuki RMX450Z 2010–2011, Yamaha WR250F 2020–2023, Yamaha YZ250F 2007–2013, 2021–2026, Yamaha YZ250FX 2020–2023, and Yamaha YZ450F 2010–2013. Fitment should be confirmed using the insert chart referenced on the page.
Built as a replacement low-volume insert kit for RS-4 mufflers, this option is intended for applications that require different sound restrictions. Yoshimura notes that decibel reduction depends on the specific application, so results can vary based on the model and setup shown in the fitment information.
This insert kit is specified as non-spark arrested. It is designed for use as a sound insert option rather than a spark arrester solution, making it important to match the insert choice to the intended riding environment and the requirements of the particular application.
The kit includes the low-volume insert tube, an end-cap collar, and a set screw. These components are intended to provide the necessary parts for installing the insert into an RS-4 muffler configuration that calls for this style of low-volume insert.
Sound
Yoshimura positions the INS-10-K as a replacement service part for RS-4 mufflers, offering a low-volume insert option for setups that need different sound restrictions. Because sound output can vary by application, confirming the correct insert selection for the specific model listed in the fitment table is an important step before installation.
This 99db insert kit is comprised of a low-volume insert tube, an end-cap collar, and a set screw. Together, these parts form the core components needed to add or replace a low-volume insert on an RS-4 muffler that uses this configuration, keeping the service process straightforward when replacing worn or missing pieces.
Fitment
Fitment is application-specific, with supported models spanning Honda, Husqvarna, KTM, Suzuki, and Yamaha as listed in the fitment table on the page. Yoshimura also advises checking the insert chart to confirm the correct match for the intended application. An installation PDF is provided on the page to guide the setup process.
| Part Number | INS-10-K |
|---|---|
| Brand | Yoshimura |
| Product Line | Replacement Service Parts |
| Series | RS-4 |
| Shipping Weight | 0.4 lb |
| Barcode | 00840025914230 |
| Make | Model | Model Years |
|---|---|---|
| Honda | CRF450R | 2009–2010 |
| Husqvarna | Norden-901 | 2022–2023 |
| KTM | 350EXC-F | 2011–2015 |
| KTM | 350SX-F | 2011–2012 |
| KTM | 790-ADVENTURE | 2019–2020 |
| KTM | 890-ADVENTURE | 2021–2023 |
| Suzuki | RM-Z250 | 2010–2014 |
| Suzuki | RM-Z450 | 2008–2014 |
| Suzuki | RMX450Z | 2010–2011 |
| Yamaha | WR250F | 2020–2023 |
| Yamaha | YZ250F | 2007–2013, 2021–2026 |
| Yamaha | YZ250FX | 2020–2023 |
| Yamaha | YZ450F | 2010–2013 |
Fitment as listed by Yoshimura for part number INS-10-K.
Instructions / What's Included (PDF)
Provided by Yoshimura. Opens in a new tab.
