High-performance heavy-duty two-stroke expansion chamber engineered to deliver robust, tractor-like bottom-end and midrange power for modern off-road and motocross applications. Constructed from tough 18-gauge carbon steel to withstand severe rock strikes, heavy trail abuse, and extreme thermal cycling while significantly improving low-end torque and throttle response.
Specs & Details
- Manufacturer Part Number: 78-1358
- Alternative Part Number: FMF 024054 / 1820-0173
- Component Type: 2-Stroke Expansion Chamber / Exhaust Pipe
- Material & Construction: Heavy-duty 18-gauge carbon steel with a nickel-plated finish
Two-Stroke Vehicle Fitment
| Make | Model | Engine Type | Year Range |
| Yamaha | YZ 250 | Two-Stroke Motocross / Off-Road | 1999–2026 |
| Yamaha | YZ 250X | Two-Stroke Cross-Country | 2016–2026 |
TSO Garage Note
The ultimate armor-plated upgrade for conquering technical single-track and heavy terrain. Swapping to this 18-gauge heavy-wall chamber transforms the power delivery by fattening up bottom-end pull and extending tractable midrange torque, effectively eliminating the harsh top-end hit in favor of meaty, tractor-like hookup while shrugging off brutal rock strikes that would cave in a stock pipe.
