Gear advice for your next ride
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Online store run by Xpert Moto
Local pickup available for pre-orders only
On-site installation at our Lewisham workshop
Online store run by Xpert Moto
Local pickup available for pre-orders only
On-site installation at our Lewisham workshop
Online store run by Xpert Moto
Local pickup available for pre-orders only
On-site installation at our Lewisham workshop
Online store run by Xpert Moto
Local pickup available for pre-orders only
On-site installation at our Lewisham workshop
Call us at: 0433 880 748
Free shipping over $200 (excludes tyres and bulky items)
Need help? book@xpertmotogear.com.au
The FMF Factory 4.1 RCT is a direct slip-on replacement for the standard muffler on the Yamaha YZ450F, WR450F and YZ450FX. It pairs an aluminium canister in a natural finish with a stainless steel midpipe and a carbon fibre end cap, and slips onto the standard head pipe.
FMF's Resonance Chamber Technology is applied both inside and outside the canister, allowing a shorter overall body that sits closer to the engine. That Factory Forward Engineering layout centralises mass and leaves less of the muffler exposed in a crash. The RTS (Rapid Tuning System) end cap arrangement makes it straightforward to swap inserts.
Built for motocross, enduro and off-road riders running a 450 four-stroke. This muffler is supplied for closed course competition use only and is not certified for Australian road use.
- FMF Resonance Chamber Technology applied internally and externally
- Shorter canister length, less exposed to crash damage than a full-length muffler
- Factory Forward Engineering positions the muffler closer to the engine to centralise mass
- RTS (Rapid Tuning System) for quick insert changes
- Aluminium canister in a natural finish with a carbon fibre end cap
- Stainless steel midpipe
- Screen-type spark arrestor insert included
- 94dB quiet insert included
- Slips onto the standard head pipe — single, slip-on configuration
- FMF states power gains across the rev range and weight savings over the standard muffler
- Manufactured at FMF's Southern California factory
- FMF part number 44443
- Factory 4.1 RCT slip-on muffler with stainless steel midpipe and carbon end cap
- Screen-type spark arrestor insert
- 94dB quiet insert
| Brand | FMF Racing |
|---|---|
| Model | Factory 4.1 RCT |
| Part number | 44443 (044443) |
| Type | Slip-on muffler |
| Configuration | Single |
| Canister construction | Aluminium |
| Finish | Natural |
| Midpipe | Stainless steel |
| End cap | Carbon fibre |
| Spark arrestor | Screen insert (included) |
| Quiet insert | 94dB insert (included) |
| Fitment | Yamaha YZ450F 2018–2024; Yamaha WR450F 2019–2024; Yamaha YZ450FX 2019–2024 |
| Fitment (later model years) | Also listed for Yamaha YZ450F through to 2026 — confirm your model year before ordering |
| Intended use | Closed course competition use only |
| Country of manufacture | United States (FMF Southern California factory) |
- Let the exhaust cool completely before washing, handling or removing it — the canister, midpipe and carbon end cap hold heat well after the engine is shut down.
- Plug the muffler outlet before washing the bike so water cannot soak the internal packing, and remove the plug before starting.
- Clean with mild soap, water and a soft cloth. Keep degreasers, oven cleaner and abrasive pads away from the natural aluminium canister and the carbon end cap.
- Wipe off mud, fuel spills and chain lube before the next ride; residue that is heat-cycled onto the canister will stain the natural finish permanently.
- Repack the muffler with fresh glass-fibre packing when the exhaust note becomes noticeably louder or throttle response goes flat — saturated or blown-out packing raises sound output and hurts performance.
- Check the midpipe clamp, mounting bolts and springs after the first ride and regularly after that; heat cycling and vibration will loosen fasteners.
- Refit the slip joint clean and dry rather than sealing it with silicone, and take care not to over-tighten the clamp on the alloy canister.
- Fit the supplied screen-type spark arrestor when riding in state forests, national parks or other fire-restricted areas where one is required by law.
- Fit the 94dB quiet insert at tracks and riding areas that enforce a sound limit; it can be removed for closed-course use where noise limits allow.
- Store the bike with the muffler dry — leaving wet packing to sit encourages corrosion inside the canister.
- This muffler is supplied for closed course use only and is not certified for use on Australian public roads.
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