High-performance lightweight two-stroke expansion chamber engineered to broaden the entire powerband from bottom to top while maximizing over-rev for classic air-cooled and early liquid-cooled YZ platforms. Constructed using lightweight 20-gauge steel for the body and thicker 19-gauge steel for the header portion, featuring hand-pounded seams to optimize exhaust gas flow and deliver classic works-bike throttle response.
Specs & Details
- Manufacturer Part Number: 78-1306F
- Alternative Part Number: FMF 020087
- Component Type: 2-Stroke Expansion Chamber / Exhaust Pipe
- Material & Construction: Lightweight 20-gauge steel body with a 19-gauge header section and bare raw metal finish
Two-Stroke Vehicle Fitment
| Make | Model | Engine Type | Year Range |
| Yamaha | YZ 250 | Two-Stroke Motocross / Off-Road | 1984–1986 |
TSO Garage Note
The quintessential works-finish pipe for breathing new life into vintage mid-80s YZ250 builds. Combining a lightweight 20-gauge body with a rugged 19-gauge header section, this chamber delivers crisp throttle snap and smooth, linear over-rev to help tame and maximize power across the entire RPM range.
