December 23, 2013
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WHAT IS IT? A bolt-on horsepower modification for the 2014 Yamaha YZ450F, with the added plus of being titanium and having a carbon fiber end cap.

WHAT’S IT COST? $1049.99 (Ti/Ti/carbon); $799.99 (stainless/aluminum/carbon).

CONTACT? or (310) 631-4363.

WHAT STANDS OUT? Here’s a list of things that stand out with the FMF Factory 4.1 2014 Yamaha YZ450F exhaust.

(1) Design. The FMF Factory 4.1 is designed to replace the stock Yamaha snake pipe on the 2014 Yamaha. The snake design allows the muffler to be moved farther forward for better centralization of mass.

(2) Price.
FMF’s 2014 YZ450F pipe actually costs more to produce than its circular Tornado predecessor?not because it uses more Ti tubing, but because it requires more exacting specs and more secure slip-fits. This year’s Factory 4.1 retails for $1049.99, while last year’s YZ450F pipe was $949.99. For comparison, a simpler 2014 Kawasaki KX450F Factory 4.1 system is only $899.99. If it were us, we’d buy the stainless steel version of the 2014 YZ450F pipe for $799.99 and forgo the Ti.

(3) Performance. In stock trim, the 2014 Yamaha YZ450F is very quiet and delivers a solid powerband that pulls from the bottom through the middle. Given that the 2014 YZ450F produces the most horsepower of any production 450cc motocross bike, you might be wondering why the MXA wrecking crew is looking for more power. The answer is that we aren’t looking for more power; we’re looking for better power. FMF’s Factory 4.1 shifts the powerband around to reduce the negatives of the stock powerband and enhance the positives. The FMF pipe calmed down the barky low-end that irritated every MXA test rider and made the smoother transition off the bottom into a broader and more usable mid-to-top. We liked the way it ran.

(4) Fixes. Out of the crate, the YZ450F is lean. With the stock pipe, MXA went richer on the fuel and advanced the ignition timing. With the FMF pipe installed, we still went richer on the fuel (although not as rich on the low end as with the stock pipe), but we left the ignition timing stock. Our maps are constantly changing, but as a rule of thumb, go richer on the fuel and experiment with the stock timing.

(5) Sound. There are actually only 660 riders in the United States whose bikes need to meet the 115 dB two-meter-max sound test (measured at 6 feet with the throttle wide open)?those riders hold AMA Pro licenses. Every other amateur or local racer must only comply with the 94 dB SAE sound standards (measured at 20 inches at 4500 rpm). Either way, FMF includes both sound and spark-arrestor inserts with every pipe to meet the standards of the day.

WHAT’S THE SQUAWK? Aesthetically, we didn’t like the fact that the FMF pipe used the stock Yamaha heat shields. Why? Because it made the $1000 pipe look like a stocker. We think FMF should have new heat shields in the works.

 This pipe is a great bargain in stainless steel and a status symbol in titanium.


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