FMF Factory Fatty Pipe 024039 — Yamaha YZ85 2002-2018

FMF Factory Fatty Pipe 024039 — Yamaha YZ85 2002-2018

Product Description

Bring authentic "works" team style and performance to your mini machine with the FMF Factory Fatty Pipe 024039. Reminiscent of the hand-crafted cone pipes once reserved exclusively for factory racing teams, this expansion chamber shares the same uncompromising material quality and elite craftsmanship. The Factory Fatty is engineered specifically to broaden and smooth out your two-stroke power curve, delivering noticeable performance boosts across the entire RPM spectrum—yielding more low-end grunt, sharper mid-range pulling power, and enhanced high-RPM over-rev.

Constructed with extreme attention to internal dynamics, FMF utilizes a lighter 20-gauge steel for the main body of the pipe to maximize resonance and crisp throttle response, while implementing heavy-duty 19-gauge steel at the header section to endure hard impacts and flying roost. Every single seam is meticulously hand-pounded to create ultra-smooth internal flow transitions. No matter your discipline—whether it is competitive motocross or demanding off-road trails—the raw finish Factory Fatty provides the competitive edge your young racer needs to pull holeshots.

Top Features: FMF Factory Fatty Pipe

• Factory Works Look: Features a bare, unplated finish with beautiful hand-pounded weld lines that replicate factory team performance styling.
• Comprehensive Power Boosting: Exponentially broadens your power band, improving low-end response, mid-range punch, and top-end over-rev.
• Dual-Gauge Steel Optimization: Employs thin 20-gauge steel for weight savings and acoustics, with rugged 19-gauge steel protection at the head pipe entry.
• Hand-Finished Seams: Ensures smooth interior wall transitions to eliminate exhaust gas turbulence and maximize raw flow velocity.

Please review the detailed compatibility data below to ensure an exact fitment match for your motorcycle before finalizing your purchase.

Fitment List

Year Range	Vehicle Brand	Vehicle Model & Sub-Model
2002-2018	Yamaha	YZ85

Frequently Asked Questions

Q: Does the Factory Fatty pipe require any special maintenance compared to a standard nickel-plated pipe?
A: Yes, because the Factory Fatty features a raw, unplated metal finish to maximize performance resonance, it is susceptible to surface rust if left unprotected. We recommend washing off mud immediately after riding, drying the pipe completely, and applying a light coating of WD-40 or anti-corrosion spray while the pipe is still warm to preserve its classic factory appearance.

Q: Will I need to re-jet my carburetor after bolting on this FMF expansion chamber?
A: Yes, since the Factory Fatty significantly increases exhaust flow and engine efficiency, adjustments to your carburetor jetting are usually required to maintain a safe, reliable fuel mixture. Check your spark plug condition or consult FMF's jetting guidelines for your specific elevation and ambient temperature settings.

Expert Pro-Tip: To guarantee an absolute airtight connection at the cylinder exhaust port, never reuse old, flattened copper exhaust crush gaskets or dried-out manifold O-rings when installing a new performance pipe. Minor exhaust air leaks draw ambient oxygen backward into the combustion chamber, which can lean out your air-fuel mixture, create harsh exhaust backfiring, and dramatically reduce the low-end throttle response you just paid for. Always install new high-temp O-rings and use a light coating of premium copper RTV silicone on the manifold coupler flange during installation.

Recommended Pairings:
o Yamaha YZ85 Performance Parts & Upgrades
o Yamaha 2-Stroke Performance Parts
o Motorcycle Chemicals

At Moto-House MX, we carry the best brands in motocross and off-road performance. Our team has over 40 years of experience helping riders get more out of their bikes. Every order ships fast from our Central Florida location.

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