FMF Parts

FMF Racing — Flying Machine Factory & American Exhaust Domination

### Brand Heritage & The Flying Machine Factory Founded in 1973 by visionary exhaust tuner Don Emler in a small garage in Hawthorne, California, FMF Racing (Flying Machine Factory) is the iconic powerhouse of American off-road exhaust engineering. Driven by the desire to build the fastest, highest-quality exhaust systems on the planet, 'Big Don' Emler transformed FMF from a grassroots Southern California speed shop into the global leader in competition two-stroke and four-stroke exhaust technology.

Headquartered in a sprawling 90,000 square-foot manufacturing facility in Rancho Dominguez, California, FMF designs, tests, and hand-builds 100% of its exhaust systems in the USA. FMF holds numerous international patents—including the revolutionary Resonance Chamber Technology (RCT) and the iconic Megabomb and Powerbomb header chambers—and has powered legendary champions to hundreds of AMA Supercross, National Motocross, GNCC, and World Enduro titles.

• Factory 4.1 RCT Titanium Slip-On Silencers: Ultralight titanium slip-on mufflers featuring carbon fiber end caps and patented Resonance Chamber Technology.
• Megabomb Titanium & Stainless Headers: Patented expansion chamber headers that boost low-to-mid power while reducing sound output by up to 1.5 dB.
• Gnarly Heavy-Duty 2-Stroke Expansion Chambers: Rugged 18-gauge stamped steel pipes engineered for tractor-like low-end torque and extreme boulder impact defense.
• Fatty & Factory Fatty 2-Stroke Pipes: Championship-winning two-stroke pipes delivering broadened, linear power across the entire RPM range.
• Powercore 4 & Turbinecore 2.1 Spark Arrestor Silencers: USFS-approved spark arrestor silencers engineered for forestry trail compliance and closed-course power.

### How FMF Exhaust Systems Outperform Restrictive Stock Exhausts 1. Resonance Chamber Technology (RCT): Factory OEM four-stroke mufflers utilize restrictive internal baffles to meet sound limits, creating severe backpressure. FMF's patented RCT chamber uses internal pulse reflection to lower decibels while simultaneously accelerating exhaust gas evacuation. 2. Megabomb Scavenging: The Megabomb header acts as an acoustic diffuser and gas expansion chamber, scavenging exhaust gases from the combustion chamber during valve overlap to increase low-end torque and mid-range throttle response. 3. Heavy-Duty 18-Gauge Steel: Stock two-stroke pipes use thin 20-22 gauge steel that dents easily. The FMF Gnarly uses ultra-thick 18-gauge steel that resists roost and boulder strikes in technical terrain.

### American Handcrafted Metallurgy Every FMF header, pipe, and silencer is hand-formed, mandrel-bent, and TIG-welded by American craftsmen in Southern California. FMF utilizes proprietary aerospace titanium blends that resist high-heat oxidation and high-grade 304 stainless steel tubing that delivers exceptional structural resilience across seasons of grueling competition.

• Silencer Repacking: Inspect and repack four-stroke silencers every 20-30 hours using FMF Premier 4-Stroke Packing to prevent canister heat discoloration and preserve sound compliance.
• Header Cleaning: Wipe raw titanium headers with rubbing alcohol before initial startup to remove fingerprints. Clean nickel-plated Gnarly pipes with mild soap and water.
• Exhaust O-Rings: When installing two-stroke pipes, always install fresh high-temperature Viton O-rings in the cylinder manifold to prevent oily exhaust leaks.
• Mounting Alignment: Loosely install all header and silencer mounting bolts before tightening to ensure the exhaust system aligns naturally without putting stress on the cylinder head exhaust studs.

Frequently Asked Questions