FMF 4.1 RCT Exhaust System Yamaha WR450F 2018
FMF Racing is the leading manufacturer of exhaust systems for cross and enduro motorcycles. This factory also makes mufflers for Yamaha under the GYTR brand. The GYTR and FMF elements differ only in the nameplate, whereas the price and quality are the same.
We brought the full FMF titanium system for Yamaha WR450F 2018, which consists of a MegaBomb pipe and a 4.1 RCT muffler with a carbon cap. The components are also available in stainless steel, which is a cheaper but a heavier solution.
Megabomb is a patented technology that increases power and reduces noise. Its shape and volume are selected so as to create back pressure at low RPM to increase power, simulating the increased length of the pipe. At the same time, it does not create resistance at over-revving, as it happens with the pipe of increased length.
The titanium muffler 4.1 RCT with a carbon cap is a racing solution optimized for minimum weight and maximum power. The muffler is equipped with Resonance Chamber Technology, which reduces noise and extends filler life. The technology lies in two inner tubes of different volumes, where the smaller one is closer to the engine and absorbs some of the noise. Also, large punches in inner tubes provide additional space for the exhaust flow, reducing resistance to increase power.
The muffler is shorter than the OEM and is located closer to the engine. That allowed us to reduce the motorcycle weight and centralize its mass in a better way. Plus, the muffler is better hidden and will not be damaged in crashes. The titanium system FMF is almost 2 kg lighter than the OEM, which makes a difference for enduro and motocross.
Installing an exhaust system is not a complicated procedure, but there are a few moments that can cause problems:
- It is important to seal all joints with a special high-temperature sealing paste for mufflers, since no clamps are used on racing systems.
- The pipe on Yamaha WR450F or YZ450F is located between the cylinder, frame, and radiators. It might take some time to pull it out, so it is better to remove the starter bracket. In the video, the motorcycle has the Moose Racing radiator protection, which got in our way. In order not to waste time, we decided to unscrew the radiator mounting bolts.
- You should begin with evenly fastening the rear pipe nuts to the cylinder, so that it fits as tightly as possible.
As written in the manual, FMF systems can be operated with standard fuel and ignition maps. To achieve the maximum efficiency, it is better to install special maps and remove the air filter restrictor. Until 2018, the WR450F required a special Yamaha Power Tuner to upload the cmap to ECU. European factory models of 2018 can be power tuned in stock, while the American ones need Competition ECU GYTR to be installed. On newer models, the map can be uploaded with a smartphone, without a Power Tuner.