The PowerCore®4 is designed to increase the horsepower and torque throughout the entire power curve and give you a noticeable power increase that is very usable and beneficial, no matter your riding style or ability. Features include space age internal packing for maximum packing life and a high-flow modular end cap. Internal core shape uses high-flow technology. Enhanced sonic evacuation provides for higher flow and increased power. Muffler includes removable spark arrestor. 97.5 dBA sound level. 95.5 dBA with QuietCore™ Spark Arrestor Insert, sold separately.
This accessory is restricted to closed-course competition use. See California Regulations regarding Emission-Related Parts and Accessories for products for closed-course competition use only.
WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov.
This all-new Factory 4.1™ Muffler incorporates the latest FMF Resonance Chamber Technology®. The patented chamber design enhances and refines exhaust pressure. Its patented core shape lowers sound level while maintaining maximum power output, and the patented canister shape increases internal volume for more sound-absorbing material. Factory Forward Engineering centralizes mass and is less prone to impact damage. Maintenance is made easy with the removal of four screws on the front end cap, and the innovative rear end cap simplifies installation of the spark arrestor (sold separately) or tuning tip inserts. Includes QuietCore™ 94 dBA insert.
Meets AMA® and FIM sound requirements. Compatible with stock or FMF® header. Built 100% in the U.S.A.
The GYTR® by FMF® MegaBomb™ Head Pipe can provide as much as a 3 hp boost, plus the MegaBomb™ actually reduces noises levels by as much as 1.5 dBA. Used by Yamaha Race Teams. The MegaBomb™ is designed to perform at the world’s highest levels of racing. It produces long header torque and short header over-rev.
The patented FMF Resonance Chamber Technology enhances and refines exhaust pressure. Its patented core shape lowers sound level while maintaining maximum power output, and the patented canister shape increases internal volume for more sound-absorbing material. Factory Forward Engineering centralizes mass and is less prone to impact damage.
This easy plug-in fuel-injection and ignition tuning tool allows riders to quickly adjust the fuel and ignition maps to suit riding conditions and rider preference. Allows nine easy-to-program adjustment points for both the fuel and ignition maps. Monitor function allows user to monitor the data from various sensors on the bike as well as adjust idle timing, see engine running time, and self-diagnosis function.
Powered by two AA batteries, thus no laptop or time consuming downloads necessary. Unit does not have to be plugged into bike to create maps. Compact design can fit in the palm of your hand, pocket, etc. Memory function can save up to nine custom maps.
NOTE: Plugs right into the YZ®450F, YZ®450FX, YZ®250FX, and YZ®250F ECU. WR®450F and WR®250F requires GYTR® Competition Kit/ECU, sold separately.
Check the Specifications tab for baseline settings.
Download the GYTR Power Tuner Race Setup Log
High-flow, two-layer foam filter offers optimized filtration while maximizing airflow. Increases performance. Filter is completely washable and reusable. Service with Genuine Yamaha Foam Filter Oil.
YZ models are for closed-course competition use regardless of modification.
Download 2018-2019 YZ450F Power Tuner Settings (Full Exhaust System + GYTR Air Filter)
Download 2019 YZ250F Power Tuner Settings (GYTR Performance Engine)
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