FMF Factory 4.1 RCT Full System For The 2018 Honda CRF250R Review

We test FMF’s dual titanium exhaust system on the all-new CRF

FMF Factory 4.1 RCT
The FMF Factory 4.1 RCT is the Southern California brand’s flagship exhaust system.Andrew Oldar

The 2018 Honda CRF250R was one of the most highly anticipated bikes of the year, and for good reason. Honda completely revamped the small-bore motocrosser with an improved chassis, coil spring Showa fork, and an all-new dual-overhead-cam (DOHC) engine. The new powerplant also features a unique dual exhaust system that is entirely separate from header to muffler. While the engine makes good top-end power, one of its shortcomings is its lack of bottom-end hit. A 250 four-stroke isn't necessarily expected to have tons of low-end pull, but even for a quarter-liter four-stroke motocrosser, the CRF could improve in this area in comparison to its competition.

mufflers for the 2018 CRF250R
The mufflers for the 2018 CRF250R uses two titanium, blue anodized Factory 4.1s with carbon end caps and retails for $1,499.99.Andrew Oldar

In an effort to coax more low-end power out of the all-new CRF, we got our hands on an FMF Factory 4.1 RCT full titanium exhaust system. The Factory 4.1 RCT is FMF's flagship exhaust system that incorporates the company's Resonance Chamber Technology, both internally and externally. FMF shortened the overall length of both CRF250R mufflers to decrease the likelihood of crash damage and to achieve what it calls "Factory Forward Engineering," which is moving the muffler closer to the engine to centralize mass. Also, the Factory 4.1 RCT system for the CRF250R uses FMF's PowerBomb header pipe, as opposed to the MegaBomb header we are more accustomed to seeing on the Factory 4.1. (According to FMF, if a MegaBomb were used, you'd only need it on one side, but using the PowerBomb on each header pipe achieves the right amount of volume and provides a better look. Win-win.)

FMF uses its PowerBomb header pipe design
Unlike most Factory 4.1 RCT exhaust systems, which commonly use the MegaBomb header, FMF uses its PowerBomb header pipe design on the CRF250R unit.Andrew Oldar

The FMF system consists of two PowerBomb header pipes and two Factory 4.1 mufflers, all of which feel significantly lighter than the stock system and are visually stunning, especially with the blue anodized finish on the mufflers. The four-piece system mounts up with zero issues, and all of the bolts line up seamlessly. Firing the CRF to life with the FMF units installed delivers a slightly louder but much deeper, throatier sound from the DOHC engine, and erases the raspiness with the stock pipe installed.

FMF units
The FMF units deliver a slightly louder but much deeper, throatier sound.Andrew Oldar

The performance gains of the Factory 4.1 system were noticeable almost immediately after entering the track. Upon exiting the first corner, the CRF with the FMF installed had a noticeably stronger bottom-end pull. In corners that previously required a decent amount of clutch slipping and in some cases even a downshift with the stock exhaust, the FMF delivered a harder-hitting and stronger low-end that transitioned more seamlessly into the midrange and got there quicker as a result of the meatier bottom-end pull. When climbing into the higher rpm, the midrange and top-end power felt comparable to stock, and we were pleased to find that neither of these parts of the powerband were compromised. The Factory 4.1 made the CRF powerband more user-friendly, easier to ride, and “filled in” the emptiness that was felt with the lacking bottom-end power from the stock system, and thereby gave it more of a linear power delivery throughout the entire rpm range.

FMF Factory 4.1 RCT full exhaust system
The FMF Factory 4.1 RCT full exhaust system gives the CRF250R some much-needed bottom-end pull while maintaining the bike’s impressive top-end power.Andrew Oldar

Aside from the FMF Factory 4.1 RCT exhaust system, our CRF250R testbike is all stock with the exception of a Twin Air air filter. With the bike being in nearly stock form, the Factory 4.1 RCT did exactly what I wanted it to do: giving the CRF250R engine’s Achilles’ heel, the lack of bottom-end power, a much stronger hit while maintaining the bike’s good midrange and top-end power. I am thoroughly impressed with the FMF Factory 4.1 RCT exhaust system and would highly recommend it to any 2018 Honda CRF250R owner who is looking for a lighter exhaust system that delivers increased bottom-end power, sounds better, and looks amazing.