2024 YAMAHA YFZ450R, MAKING IT EVEN BETTER!

YAMAHA YFZ450R, MAKING IT EVEN BETTER!

Stage 1: Duncan Racing performance upgrades and more By the staff of Dirt Wheels

It’s time to begin upgrades to our 2024 Yamaha YFZ450R from the July 2024 cover of Dirt Wheels. For stage one of this build, we’re installing protection mods for the technical trail rider and bolt-on performance mods that provide gains everywhere. For this part of the build, we headed to Duncan Racing in El Cajon, California, one of the industry’s oldest and best ATV performance shops. These parts are manufactured by or available from Duncan Racing with their pricing.

Lenny Duncan, shop manager and host of the ATV-TALK podcast, helped us assemble this build, but all these upgrades are easy enough to install with standard tools and some mechanical knowledge. We can’t stress enough the importance of following instructions, especially when using a torque wrench. Do not over- or under-tighten fasteners. Performance mods are all designed to be compatible with 91-octane pump fuel. However, we recommend a fuel free of ethanol, which can harm intake components over time. Pump-fuel blends also vary, so we’re running 95-octane race fuel for consistency and cooler running-engine temperatures, and it won’t go bad over extended breaks.

DUNCAN RACING FAT BOY 4 COMPLETE POWER EXHAUST

Duncan’s Fat Boy 4 complete exhaust system has been a front-runner at the motocross track and cross-country racing scene for decades. It allows the YFZ450R to exhale freely without all the restrictions found on the stock exhaust. Duncan claims a 10-plus-horsepower increase when appropriately tuned, along with a higher-flowing air filter kit, which we’ll get to in a moment. The difference is massive, with faster acceleration and solid gains from idle to top speed. The exhaust is well-built with a stainless header pipe, repackable aluminum muffler body, and CNC-machined billet aluminum end caps and muffler mounts. The entire system mounts together rigidly with an O-ring seal, so there’s no movement between joints, ensuring leakproof connections from front to back. It’s a popular performance upgrade with power gains everywhere. We opted for the optional billet turn-down required for spark arrestor installation. 

Price: $799.95

1. VORTEX IGNITIONS ENGINE CONTROL UNIT

Duncan Racing is the USA importer for the highly popular Vortex ECU (Engine Control Unit) and has been for over 25 years.. The Vortex ECU comes pre-loaded with 10 selectable, high-performance fuel-ignition maps (no need to dyno tune). The ECU is a plug and play design and very simple to install using the stock ECU connector. Built into the Vortex ECU map are 4 dials; 1-map selector dial and three fuel-trim switches can be accessed to fine-tune low-, mid- and high-range fuel metering. The Vortex also increases the rev limit on select maps. Adjusting the ECU and dialing in switches with a screwdriver is very simple. While intake and exhaust mods are great for performance they must have proper fuel and ignition curve to really perform. The Vortex takes performance to a new level, and you can feel it the first time you stab the throttle. “I like map nine, even on a built or stock bike, because I believe it gives you the best overall power,” claims Duncan.  “With the exhaust and intake combination that we are running and map nine, I like the rideability with increased acceleration out of the turns and how it handles through the mid-range and revs out on top. It gives you a better, broader feel.” Vortex offers a 1-year limited warranty. The unit is designed for closed course competition and not intended for highway use.

2. PRO DESIGN PRO FLOW FILTER KIT

Pro Design’s Pro Flow kit has a proven clean-air track record and remarkable gains in performance, especially when used without the stock airbox lid. The billet flange seals to the stock airbox for use with your choice of a clamp-on Pro Design foam filter or pleated cotton filter. There’s no need for filter grease; tighten the hose clamp on your clean and oiled filter, and you’re ready to ride. The kit includes the billet flange with an O-ring seal, all hardware and your filter choice. 

Price: $199.95

3. GPR V5 STEERING STABILIZER

The fifth generation of GPR stabilizers is significantly better for sport ATV use with a stronger vein (arm inside that passes through the fluid) than former generations. It also gets more leverage with a mount at the bottom of the steering stem and provides better shock absorption for the rigors of ATV use. The top dial allows the rider to select the required resistance for different terrains. You’ll want a lighter setting in the dunes, while a stiffer setting provides less effort at the bars when hitting rocks, tree roots and other hard edges. This is one of the best products you can buy to reduce arm fatigue and enhance endurance, whether riding or racing. 

Price: $749.95

4. DUNCAN RACING FRONT BUMPER

Available in triple-plated chrome or black, Duncan Racing’s front bumpers are lightweight and provide gripping locations when lifting the front end of the ATV. They’re made from mild steel with professional-grade heli-arc welds. One of our favorite design features is the bumper sits behind the front of the tires so that it won’t rub the front of your truck bed during transport. All necessary hardware is included. 

Price: $249.95

1. WORKS CONNECTION HOUR METER

This simple-to-install tool makes tracking maintenance much more convenient. It has a resettable maintenance timer, rpm display, and max rpm recorder that resets after each ride. It also keeps track of the total hours of operation. It mounts to any flat surface, or you can purchase the optional WC mounting bracket. On the YFZ450R, we mounted ours inside the right-side radiator shroud, where it’s well protected but still easy enough to read and reset. 

Price: $89.95

2. WORKS CONNECTION ENGINE PLUGS

Works Connection engine plugs do more than look cool. They’re machined from 6061 T-6 aluminum to be stronger and more leak-resistant than the stock plastic plugs. Installation only requires a #6 Allen wrench and the stock O-ring. If you elevate the left side of the YFZ, you can complete the installation without draining the oil. Available in blue, red, black or purple for the YFZ. 

Price: $44.95

2. DUNCAN RACING OIL BREATHER OVERFLOW TANK

The breather kit includes the aluminum oil-catch van, breather hold-down, rubber oil lines, hose clamps, and the AIS (air induction system) delete plate. Unlike Duncan’s aluminum can, the stock overflow can is prone to cracking and leaking. However, the most significant performance benefit is the AIS delete plate, which opens the airways by eliminating air emissions controls. The YFZ breathes better, resulting in more responsive performance, especially in the power curve’s low- and mid-range points. 

Price: $305

3. CRF CHASSIS SKID 

Campbell Racing Fabrication poly ATV skid plates offer lightweight but maximum protection with 1/2-inch thickness, oil drain-plug access, and all necessary hardware using wide-sunken frame fasteners for a solid and dependable fit. They are a favorite skid plate for pro riders in every racing discipline. The skid plates are available in red, white, blue, yellow or black. 

Price: $225

1. HESS ROTOR GUARD

We replaced the weak plastic swingarm skid plate with stronger billet guards that withstand the abuse of boulders and logs over challenging terrain. A lightweight Hess rotor guard was installed on the brake side to protect the disc fully. The rounded bottom surface is designed to easily slide over terrain and enhance ground clearance, unlike a traditional aluminum skid plate that can hang on rocks and roots. 

Price: $175

2. ATV-TALK SPROCKET GUARD

Lenny Duncan, the host of the ATV-TALK podcast, offers these billet-aluminum ATV-TALK sprocket guards, which protect the chain and rear sprocket. Like the brake side, ground clearance is enhanced compared to a traditional skid with the guard mounted directly to the sprocket. 

Price: $99.95

3. UPP RACING SPROCKET GUARD CASE SAVER

Made in the USA, UPP’s front sprocket guard case saver is built to withstand the impact of a thrown drive chain, protecting the engine case and side cover from catastrophic damage. It’s cheap insurance that could save you thousands of dollars in repair bills. 

Price: $49.95

VERDICT

The YFZ450R was already impressive in stock form, but the difference a few bolt-on products made took performance up several notches—it rips! Power is plentiful everywhere without any sign of hesitation, flat spots or lean fuel consumption. It accelerates strong out of the corners, and weight savings are noticeable with a more flickable feel when trails get tight. Likewise, our confidence to stay on the gas is improved with added protection from the front bumper to the tail, and our new GPR stabilizer tames blows and saves arm strength when the going gets rough. It’s a better machine for whatever we throw at it on the track, at the dunes and out on the most rugged trails.

Next, we’ll add some more bolt-on goodies like nerf bars, a grab bar and other accessories from DBR Racing, and we’ll install some extreme trail-rated tires with plenty of sidewall protection. After that, we will improve the YFZ’s already excellent suspension. Stay tuned! ο

CONTACTS

Duncan Racing: www.duncanracing.com, (619) 258-6306

Vortex: www.vortexcdi.com

Pro Design: www.prodesignracing.com

GPR: www.gprstabilizer.com

Works Connection: www.worksconnection.com

Campbell Racing Fabrication: www.campbellracingfabrication.com

Hess Motorsports:www.hess-motorsports.com

Yamaha: www.yamahamotorsports.com