MOTOCROSS ACTION PRODUCT TEST: FMF FACTORY 4.1 2010 CRF250 EXHAUST WITH MEGABOMB HEAD PIPE:

March 23, 2010
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WHAT IS IT? It’s FMF’s premium offering for the new, fuel-injected CRF250.

WHAT’S IT COST? $899.99 (titanium).

CONTACT? www.fmfracing.com or (310) 631-4363.

WHAT STANDS OUT?
Here’s a list of things that stand out with FMF’s Factory 4.1 CRF250 exhaust system (with MegaBomb head pipe).

(1) Performance. The FMF Factory 4.1 maintained the stock CRF250’s oomph in the lower rpm range?which is just enough to help get into the midrange. The stock CRF250 powerband is at its strongest in the middle, but weak on the low end and flat on top. The Factory 4.1 starts to do real business in the midrange and carries more power up into the top-end. With the Factory 4.1 and MegaBomb header, the power spread is very metered. There is no abrupt hit or arm-jerking acceleration. Instead, the FMF pipe makes the bike easier to ride and spreads out the power delivery so that test riders can shift less often. The power delivery is broader, slower-revving and mistake-proof.

(2) Sound. With a resonance chamber in the MegaBomb head pipe and another at the leading edge of the muffler, the FMF pipe was extremely quiet (and not just at the AMA’s ridiculously low sound test rpm). Every MXA test rider commented that where the stock muffler emitted a shriek at a specific rpm, the FMF Factory 4.1 emitted more of a high-pitched hum. If you want a little more oomph from the Factory 4.1 and don’t ride at a closed-course racetrack, you can remove the insert from the stinger.

(3) Installation. All the bolt holes align perfectly, and installation is a snap.

(4) Fit. The resonance chamber at the leading edge of the muffler has more girth than the stocker. It came in contact with the CRF250 number plate panel and melted it. FMF says that we misaligned the spacers and that this is typically not a problem.

(5) Weight. The titanium FMF Factory 4.1 muffler and MegaBomb header weigh 5.4 pounds. The stock header and muffler are 6.25 pounds. The 4.1 titanium system saves almost one pound (despite its more complex design).

(6) Bells and whistles. Our system bristled with trick features: It was full titanium, had a blue-anodized finish, featured two resonance chambers, came with a “remove before flight” bung to keep out water during washing, and even had a protective end piece for the end of the pipe when not mounted to the bike (we appreciate it because it’s handy for us during testing).

WHAT’S THE SQUAWK? Two quibbles: (1) The rear resonance chamber melted the CRF250 side panel (so be very careful when installing it). (2) The smoothness of the power delivery lacked a vivacious personality.


FMF’s Factory 4.1 with MegaBomb head pipe makes your CRF250 more powerful, easier to ride, smoother and quieter by making the power delivery more metered.

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