Yoshimura · RS-4
The Yoshimura RS-4 Premium Muffler Repack Kit is a replacement service parts package designed to refresh RS-4 off-road mufflers so they continue to operate as intended. Yoshimura notes that off-road systems should be repacked after 6-8 hours of use, or after each Race, to help maintain proper exhaust function.
By replacing dirty packing that can restrict airflow, this kit supports freer airflow from the motor, helping restore lost power and improve exhaust sound as the manufacturer describes. See the fitment table below for the specific GasGas, Honda, KTM, Suzuki, and Yamaha models and model years supported.
This kit includes Yoshimura Silent Sport Premium Packing Material to replace worn or contaminated muffler packing. Yoshimura explains that dirty packing can restrict airflow from the motor, contributing to a loss of power and degradation of sound, making timely repacks an important part of routine off-road exhaust service.
Along with packing, the kit includes RS-4 identification pieces to update the look of the canister after service. Contents include an RS-4 End-cap and Canister Decal (RS4-NB003 & RS4-NB004 x 1 QTY) plus an RS-4 Badge (RS4-NB001 x 1 QTY).
The kit includes key hardware intended for the repack process: Rivet Band (LC4.5T x 2 QTY) and Stainless Rivet (C3-RIVET x 8 QTY). With these components in the box, it supports a more complete service of a Yoshimura RS-4 muffler during scheduled maintenance.
Performance
Yoshimura emphasizes that repacking at the suggested intervals is essential for an exhaust to perform the way it was designed. The manufacturer states that off-road systems need to be repacked after 6-8 hours of use, or after each Race. As packing gets dirty, it can restrict airflow from the motor, resulting in a loss of power and degradation of sound.
Sound
According to Yoshimura, repacking the muffler allows for freer airflow from the motor, which restores lost power and improves the exhaust sound. This RS-4 Premium Muffler Repack Kit is built around that maintenance goal, providing the packing material along with related RS-4 decals, badge, and included rivet bands and rivets listed in the product contents.
Fitment
This repack kit is specified for a range of GasGas, Honda, KTM, Suzuki, and Yamaha applications as listed in the fitment table. An installation PDF is provided on the page for reference during service, helping ensure the repack process follows the intended steps for the RS-4 series.
| Part Number | REPACK-RS4-ADV |
|---|---|
| Brand | Yoshimura |
| Product Line | Replacement Service Parts |
| Series | RS-4 |
| Shipping Weight | 1 lb |
| Barcode | 00840025913776 |
| Make | Model | Model Years |
|---|---|---|
| GasGas | EX-250F | 2023 |
| GasGas | EX-350F | 2021–2023 |
| GasGas | MC-250F | 2021–2023 |
| GasGas | MC-350F | 2022–2023 |
| GasGas | MC-450F | 2022–2023 |
| Honda | CRF250L | 2013–2020 |
| Honda | CRF250L-Rally | 2017–2020 |
| Honda | CRF450R | 2011–2012 |
| Honda | CRF450X | 2019–2026 |
| KTM | 350EXC-F | 2011–2015 |
| KTM | 350SX-F | 2011–2015 |
| KTM | 450SX-F | 2012–2014, 2019–2020 |
| KTM | 450SX-F-FACTORY-EDITION | 2012–2014 |
| KTM | 450XC-F | 2013–2015, 2020 |
| KTM | 450XC-W | 2012–2015 |
| KTM | 500EXC | 2012–2015 |
| KTM | 500XC-W | 2012–2015 |
| Suzuki | RM-Z250 | 2010–2018 |
| Suzuki | RM-Z450 | 2008–2017 |
| Suzuki | RMX450Z | 2010–2011 |
| Yamaha | WR250F | 2023 |
| Yamaha | WR250R | 2008–2020 |
| Yamaha | WR450F | 2012–2014 |
| Yamaha | YZ250F | 2007–2017, 2024–2026 |
| Yamaha | YZ250FX | 2015 |
| Yamaha | YZ450F | 2010–2013 |
Fitment as listed by Yoshimura for part number REPACK-RS4-ADV.
Instructions / What's Included (PDF)
Provided by Yoshimura. Opens in a new tab.
