FMF Gnarly 2-Stroke Pipe
MSRP: $289.99
$231.99
Exact Fitment Guarantee
The FMF Gnarly 2-Stroke Exhaust Pipe is the legendary heavy-duty expansion chamber engineered for modern two-stroke motocross and enduro riders who demand rugged rock impact protection and enhanced low-to-midrange torque delivery. Standard OEM two-stroke pipes are stamped from lightweight 20-gauge or 22-gauge steel, leaving them extremely vulnerable to roost dents, boulder crushes, and log strikes that restrict exhaust airflow and ruin engine performance. The FMF Gnarly resolves this by utilizing rugged, heavy-duty 18-gauge steel construction throughout the entire chamber body.
The engineered geometry of the Gnarly pipe alters the internal pressure wave reflection timing within the convergent and divergent cones. By tailoring the acoustic return wave to arrive earlier at the exhaust port, the Gnarly dramatically boosts bottom-end pull, tractor-like grunt, and strong midrange power delivery, transforming high-revving two-strokes into smooth, manageable woods and hard-enduro conquerors. The exterior is finished with FMF's durable nickel-plating process, which resists surface rust, corrosion, and mud staining, maintaining a bright, professional finish season after season.
- Material Construction: Super-tough 18-gauge heavy-duty stamped carbon steel
- Surface Finish: Bright nickel-plated corrosion-resistant coating
- Power Curve Profile: Bottom-end and midrange torque emphasis for woods and technical terrain
- Sealing System: Dual high-temperature Viton O-ring manifold spout interface
- Welding: Precision hand-welded stamped cone seams
### Step-by-Step Installation & Safety Protocols Installation begins with removing the existing pipe and springs using an exhaust spring puller tool. Remove the silencer connection and frame mounting bolts. Inspect the rubber vibration dampers on the frame mounts and replace any that are perished. Replace the high-temperature Viton O-rings inside the cylinder exhaust manifold spout. Apply high-temperature grease to the new O-rings and slide the FMF Gnarly pipe spigot into the cylinder exhaust port. Secure the pipe using fresh swivel-hook exhaust springs. Align the rear stinger outlet with the silencer rubber coupler, loosely install all frame mounting bolts, ensure the pipe does not rub against the radiator or frame cradle, and tighten all hardware to 18-20 Nm.
### Maintenance & Rust Prevention Maintenance involves checking exhaust manifold O-rings for oil weeping (indicating exhaust seal wear) and washing the nickel-plated surface with standard soap and water. Minor carbon buildup inside the chamber can be flushed during annual rebuilds.
Frequently Asked Questions
Q: Does the Gnarly pipe reduce top-end power on a two-stroke?
A: Because the Gnarly is tuned to deliver massive bottom-end and midrange tractability, it shifts the power curve downward, slightly softening extreme top-end over-rev in exchange for superior lugging capability in technical terrain.
Q: What is the thickness of the steel used in the FMF Gnarly?
A: The Gnarly is stamped from robust 18-gauge steel, making it substantially thicker and more dent-resistant than stock OEM pipes or standard lightweight race pipes.
Q: Do I need to re-jet or re-map my carburetor/EFI system with the Gnarly?
A: In most applications with modern fuel injection (TPI/TBI) or standard jetting, the Gnarly runs smoothly on baseline settings, but rich conditions in humid or high-altitude environments may benefit from one clip position leaner on the needle or a slight fuel trim adjustment.
Q: Will the Gnarly pipe mate to my stock silencer?
A: Yes. The Gnarly pipe is engineered with standard factory stinger dimensions, allowing it to connect directly to the OEM silencer or any FMF two-stroke silencer (Powercore 2, Turbinecore 2, or Shorty).