Yoshimura · RS-4D
The Yoshimura RS-4D Sound Insert Kit (INS-BD-K) is a replacement low-volume insert kit designed for RS-4D mufflers that use the bottom outlet at the RS-4D end-cap. It’s intended for riders who need an optional insert setup on applications that call for different sound restrictions, with overall decibel reduction varying by application.
This kit is listed for Honda CRF250R 2011–2013, Honda CRF450R 2011–2012, and Yamaha YZ450F 2010–2013. Fitment details are application-specific, so the fitment information on the page should be reviewed before ordering.
Built as a replacement low-volume insert kit for Yoshimura RS-4D mufflers, INS-BD-K is intended for the bottom outlet configuration at the RS-4D end-cap. It’s a focused service part for maintaining or adjusting an RS-4D setup without changing the muffler itself.
Yoshimura lists this insert kit as an optional solution for applications that require different sound restrictions. Because decibel reduction depends on the specific application, results can vary by bike and setup, making it important to confirm the correct insert for the intended use.
This insert kit is supplied with the low-volume insert tube, an end-cap collar, and a set screw. These parts are intended to support installation into the RS-4D end-cap bottom outlet configuration as a complete insert kit package.
Sound
This kit is intended for the bottom outlet of the RS-4D end-cap. That detail matters when selecting an insert, since RS-4D configurations can differ by application. Reviewing the fitment information shown on the page helps ensure the insert kit matches the correct outlet style before installation.
Installation
Yoshimura lists this insert kit for Honda CRF250R 2011–2013, Honda CRF450R 2011–2012, and Yamaha YZ450F 2010–2013. The manufacturer notes that decibel reduction depends on application, so results can vary. For installation guidance, the page includes an installation PDF to reference during the setup process.
| Part Number | INS-BD-K |
|---|---|
| Brand | Yoshimura |
| Product Line | Replacement Service Parts |
| Series | RS-4D |
| Shipping Weight | 0.35 lb |
| Barcode | 00840025917606 |
| Make | Model | Model Years |
|---|---|---|
| Honda | CRF250R | 2011–2013 |
| Honda | CRF450R | 2011–2012 |
| Yamaha | YZ450F | 2010–2013 |
Fitment as listed by Yoshimura for part number INS-BD-K.
Instructions / What's Included (PDF)
Provided by Yoshimura. Opens in a new tab.
