High-performance heavy-duty two-stroke expansion chamber engineered to deliver robust, tractor-like bottom-end and midrange power for classic steel-frame 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: 78-1090
- Alternative Part Number: FMF 020302 / 1820-0082
- Component Type: 2-Stroke Expansion Chamber / Exhaust Pipe
- Material & Construction: Heavy-gauge 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 | 1997–1998 |
TSO Garage Note
The essential armor upgrade for reviving the bottom-end snap on vintage steel-frame YZ250s. Swapping to this heavy 18-gauge chamber thickens up low-end torque and smooths out the power delivery for technical trail work, while shrugging off the heavy impacts that would instantly crush a thin stock expansion chamber.
