Going all in with Yamaha’s multi-championship sport ATV! By Rob Baumsteiger Photos by by Sam Holmes and Jeff Henson

The only complaints we have about this build come when it’s time to load it back up in the truck and head home. It’s an addicting rush of a ride!

The build started with a new 2023 Yamaha YFZ450R Special Edition purchased from Nash Powersports in Phoenix, Arizona. From there, the build was brought to DirtFiend Racing (DFR) in Mesa, Arizona, for a complete makeover. The team at DFR has been building and helping maintain ATVs, motorcycles, UTVs and three-wheelers since 1997. For this build, the goals were to create a motocross racer that by waking up the YFZ450R with some bolt-on external motor modifications and enhance this ATV’s already great suspension and handling characteristics. 



The first call was to RP Race Performance out of Canada. Over the past few years, RP Race has developed a great name in the off-road industry for its consistent development of quality products and support of the ATV community. We ordered their EFI Intake system, as we wanted something that worked with the stock airbox. To go with the new intake system, we chose the standard complete exhaust system and had the exhaust can Cerakoted (ceramic) black to give the exhaust a little different look. The quality of their products was beyond our expectations. Everything about their product showed the passion and attention to detail needed when building a top-tier ATV. 

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Now that the intake and exhaust had been changed, we needed to add the Vortex ECU to help tune the motor for our modifications. We also added numerous parts from 38 Motorsports, including their oil breather box, AIS block-off kit, speed sensor block-off, and other products they offer. The last addition to our engine package was replacing the stock clutch system with the (09-10) Hinson BTL slipper complete clutch kit and adding the billetproof clutch cover. 

2024 marks 20 years since the original all-steel-framed YFZ450 made waves at the track. To celebrate, Dirt Wheels contributor Rob Baumsteiger and DirtFiend Racing built this masterpiece.


With the motor package at the level we wanted, it was time to focus on the suspension and handling characteristics of the quad. The Yamaha is already a great-handling quad and can be raced at most levels in stock form, but for this build, we wanted to make it better! 


We chose Walsh Race Craft with PEP Suspension regarding suspension and handling characteristics. Walsh Race Craft has been leading the charge in suspension and handling for over a decade, and many of the top racers in the world choose Walsh. Mike and his team constantly improve their product; they have never been a company to say that something is good enough, and this was what we wanted in our build. After some conversations with their team, we decided that, based on our skill level, the motocross A-arm package and standard-length swingarm with the G2 linkage was the direction we wanted to go. We added a subframe and +.5 / +1 steering stem with the handlebar clamps. PEP Suspension wrapped up the suspension side with front PB1 shocks and a ZPS rear shock. An RPM Dominator II axle with a sprocket hub was also included to finish off our chassis modifications.

Moving into this build’s final stages, we had to find the right wheel and tire package. With so many choices out there, we had to do some research and chose to go with Douglas wheels and CST Pulse MXR tires. This package seems to be the winning combination of most of the pro motocross teams, and we wanted to know what the hype was all about. Factory 43 is where we landed on the front bumpers, nerf bars and grab bars. With any build, no matter what type of riding you do, it is necessary to add a steering stabilizer and a good set of handlebars, and we chose the Precision Pro stabilizer and Fasst Co. Flexx handlebars.

On the track, this YFZ450R carves corners and cuts through the chop like a knife going through butter.


As we completed our goals for this build, we realized that the quad was missing something that made it stand out from the rest of the pack. The Special Edition graphics on it would not do for the time and money we put into this build. We needed something flashy and something exciting. Sam at DirtFiend Racing took on that challenge and created a graphics kit that exceeded our expectations. The graphics kit matched perfectly with the orange, gray and black lines on the Yamaha but with a twist. The holographic addition to the graphics made the quad look alive and fast while standing still. It was the perfect final piece to bring this build to life, and it blew away our expectations. It was time to see if all the money, time and hard work paid off. Let’s put this beauty to the test!

Engine internals are stock, but an RP Race Performance EFI intake system, Vortex ECU and numerous products from 38 Motorsports unlock much more of the engine’s potential.


Now that the build was completed, we needed to see if all the money and time was worth it. We headed out to Twisted Lizard Speedway in Arizona. This is a new MX track that not only allows ATVs and three-wheelers to ride, but also encourages them to come out! The track layout was fast with high-speed turns, presenting an excellent opportunity to push our build and see what it was capable of. Within the first few laps, we could tell a night-and-day difference with the motor modifications. The engine was alive and barked at the slightest push of the thumb throttle. There was no hesitation in the motor, and it felt faster than some modified motors we’ve raced. As we got more comfortable with the track and the quad, we could see what all the hype was about with the Walsh/PEP combo. You could set the quad into the turn at almost any speed, and it would stick. The YFZ had no body roll and reacted like it wanted to be pushed even faster. Not once did we feel that we were exceeding the limits of the machine. Each time we dove into a turn, the suspension and chassis soaked up everything we threw at it, and then asked for more. The wheel and tire combo were also perfect, and we now understand why so many pro riders are choosing this package. The most impressive thing about this build was how solid it felt when hitting rough sections. The quad stayed planted and soaked up everything without getting out of control or the rear end wanting to bounce around. Overall, this was a great first impression, leaving us with a smile from ear to ear and an addictive desire to ride more!












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