Fit for the MX trackBy the staff of Dirt Wheels

When building his MX quad, Logan Huff set the suspension up and chose tires that would keep the YFZ lower and better able to make fast, flat turns to make time on the track.

Yamaha’s YFZ450R rolls off the showroom floor ready for high-performance riding and racing. It serves as a great platform for ATV competition of all levels. Utah’s Logan Huff is a top pro racer in the West Coast-oriented WORCS Grand Prix series. After years racing Yamaha’s finest sport machine, Huff learned what gets him across the finish line with speed. However, he wanted to take on motocross racing to help hone his craft and become even faster in the WORCS Pro ATV class. Logan tackled a motocross build, and we got to see his YFZ450R up close the week before his big adventure to Tennessee. He raced the infamous ATVMX National at the Loretta Lynn’s Ranch. 

When racing is taken to the top level, machine setup becomes crucial. Pro racers split hairs in all areas to squeeze a little more performance out of the quad to be more competitive. MX calls for a different machine setup for the motor, suspension, chassis and cockpit. Huff has fortunately spent time rubbing wheels in the Quadcross Northwest series, so he has a great understanding of what it takes to have a quick MXer.

There are jumps in WORCS racing, but a motocross quad does a lot more airtime. The wide stance, Elka suspension, and Fasst Flex handlebar all make flying and landing comfortable.


A WORCS pro machine requires a good balance of power and reliability for the 90-minute race. In motocross, big horsepower and high torque are ways to grab a good start and to clear massive jumps during the relatively short motos. Some changes were in order.

More internal motor work was the first requirement. Huff builds all his quad’s motors, but he relies on companies like Fastheads for specialty work he can’t easily do. Fastheads performed a full port and polish on his cylinder head, and five-angle-cut the valve seats to fit 1mm oversized Del West titanium intake and exhaust valves. Lifting the valves open are a pair of Stage 2 Hot Cams with CV4 valve springs. A Vertex high-compression piston mounted in a Cylinder Works cylinder compresses all of the extra air coming in.

Out of habit, Huff likes to keep his engine reliable, so he left the bottom end OEM, except for the Hinson Racing conventional clutch. Hinson’s full kit includes a new clutch basket, inner clutch hub, pressure plate, friction and steel clutch plates, springs and a new clutch cover to fit the bigger clutch.

Huff clamps a Twin Air Power Flow air filter to a Fuel Customs intake, which allows the Yamaha motor to breathe properly after the motor work. An FMF stainless Factory 4.1 full system, which includes an FMF Powercore header, was installed to help exhaust the burned fuel particles.

A lot of attention is spent on the controls. Fasst Company’s Flexx handlebar has elastomers that are the final suspension for the rider’s hands. They make a huge difference.
Huff has the YFZ engine ported by Fastheads with oversize valves, a Vertex piston, Hot Cams, a Fuel Customs intake and an FMF pipe. He was surprised how built all the MX engines were.


Tuning gets the most power, life and reliability out of your motor package. Rather than making mechanical adjustments to a carburetor, throttle bodies with fuel injection allow tuning fuel output and ignition spark electronically. Huff chooses PEP Performance to tune his Vortex ECUs after making any motor changes. Dyno tuning is not a cheap service, but it’s hard to deny it makes a huge difference.

When motors are pushing a high-compression piston, hotter cams and a stronger spark, cold-cranking amps are a big help for startup. The OEM Yuasa battery only puts out 90 cranking amps, which is fine for a stock motor. The Anti-Gravity AG-801 lithium battery offers 240 cold-cranking amps. That fires this built Yamaha up without a fuss.

Fuel Customs makes a dedicated intake system for the YFZ. It uses an easy-to-service foam filter. Huff’s MX quad is more powerful than his WORCS one but still reliable.
C&J Powdercoat in St. George finished all of the chassis components in Satin Black. RPM makes the Dominator axle and Campbell Racing the protective sprocket guard.


With great power comes great responsibility. Putting the power to the ground are GBC Mini Master tires, stuffed with Tire Blocks and mounted on 4:1 offset GPS beadlock wheels! Typically, in ATV motocross, 18-inch rear and 20-inch front tires are the sizing of choice for 450cc machines. The shorter tires add torque off the start gate, help corner execution and offer shorter gearing for the tighter situations found on motocross tracks.

You rarely have to worry about large rocks or a wide variety of terrain on a motocross track. The smaller tire size will lower your quad’s ride height about an inch. You still need frame and component protection for deep ruts and hard landings. Logan installed a Campbell Racing Fabrication chassis skid plate on the bottom of his Yamaha, and it’s been used and abused already. A Glann Innovations case saver and chain slider were paired with a Campbell Racing Rut Buster sprocket guard to protect the drivetrain. A Sunstar 520XTG works chain and steel sprockets drive power to the rear wheels.

An RPM Dominator II axle is trusted for the big sends and abuse, not to mention that added width that is beloved on a motocross build. A wider platform lets you corner much faster with less worry about tipping your quad onto its lid with you under it.

Since MX races are shorter than WORCS events, the riders slam bumps harder. Here, Huff is pounding through aggressive chop. This quad is built to handle the punishment.


In the suspension department, Logan installed a pair of Elka Stage 5 Shocks on Roll Design long-travel control arms up front. Out back is an Elka Stage 5 shock held up by the MX Teixeira Tech linkage connected to a stock swingarm. Coming from Huff’s typical off-road setup, some changes were made to get this YFZ450R tuned specifically for moto. Elka stiffened up the valving for the big jumps and hard landings. They also lightened the spring rates to lower the quad’s ride height to help maintain a low center of gravity. To help with cornering, the front shocks were slightly shorter than the WORCS setup as well.

Talk about handling and it takes us to the Fasst Company 14-degree Quad Low Flexx handlebar. The Flexx bar is mounted on the stock steering stem to keep the bar height low. Keeping the hands protected and controls clear of mud are a set of PowerMadd Sentinel handguards. A Works Connection Elite clutch perch controls the Hinson clutch. A Pro Design tether kill switch is installed as a requirement for the racing series Logan competes in. An RMZ kill button replaces the stock start-button cluster to clear up some space on the bar. And last, on the handlebar are Oury full-waffle ATV grips that are wire-tied on.

Rath Racing’s competition nerf bars are mounted to the YFZ with Walsh Race Craft’s 0.25-inch lower footpeg studs. To support a lower center of gravity, a Walsh Race Craft 0.75-inch lower six-point subframe is preferred. Zip Racing’s Lo-Boy seat foam and custom Lo-Boy seat cover with Huff’s name in the design makes it easier for him to stay in the saddle when he gets tired.


Sitting on this machine feels noticeably lower than the typical sport quads we test on the West Coast. Although the ride height is low, the Elka shocks soaked up big hits with ease while feeling absolutely planted to the ground. We even came up short on a couple of jumps, and it was hard to get them to bottom.

Huff’s plan was to get the bike low stiff but make sure there was clearance when it bottomed. Rath pegs and nerfs give a secure footing for impacts. SSi Decals made the graphics kit.

The suspension is rough in the chop and potholes, which really let the Flexx bars shine. We missed having a steering stabilizer on the quad. Steering stabilizers help keep the wheels pointed in the direction you want them to be by keeping the bars straight when you hit unrelenting terrain.

The Zip Racing seat made it extremely easy to stay in the saddle and put power to the ground. We could see how the flatter profile and extra space from the cutout are beneficial while cornering. The Rath pegs are very sharp and keep your feet glued to the pegs. Walsh’s lowered peg studs made it easier to stand up coming out of turns, but you certainly are shy some ground clearance under the nerf bar and peg.

The GBC Mini Master tires are a four-ply tire and a little stiffer than your typical motocross tire, but they still worked great in the hard-packed soil we were on for our test day. The foam tire inserts called Tire Blocks help make great traction by allowing lower tire pressures and are a huge benefit to finish motos without getting a flat.

The motor package and tuning were phenomenal. The quad absolutely rips. PEP Performance spent a couple of well-utilized hours on the dyno with the quad and did a really good job getting Logan’s YFZ dialed in. Performance like this comes with a price tag, but it’s easy to justify when you’re racing at the top level. Not all these modifications are needed for the weekend warrior, and we don’t need to break the bank just to take the quads with us on our camping trips. The experience from a package put together like this is unlike any other quad you’ve ridden.

We got Huff on the phone after he raced all weekend at Loretta Lynn’s and really put the new setup to the test. He mentioned the motor still needed more power. The only real motor change he made from his WORCS setup was the 1mm oversized intake and exhaust valves. He was hoping that would do it, but it quickly showed he was lacking power compared to the other quads on the track. He really liked how the stiffer suspension felt. It helped the quad stay up in the deep and rough testing conditions Loretta’s has to offer. All in all, he learned a lot, and plans to go back one day more prepared than he was in 2021!

Between the extensive powdercoating and the clean SSi graphics, Huff’s YFZ has a clean and purposeful look to it. It is as capable as it looks.


AMERICAN STAR RACING: (435) 562-4386,

1” brake line clamps: $17.95 per pair


AG-801 small case lithium battery: $179.99


1/2” skid plate: $130

3/4” sprocket guard: $70

CYLINDER WORKS: (515) 402-8000,

Standard bore HC cylinder kit: $556.26

C&J POWDERCOAT: (435) 673-6565,

Powdercoat & sandblasting: $860

DUNCAN RACING: (619) 258-6306,

Oil recovery tank: $149

Vortex ECU: $749.99

ELKA SUSPENSION: (800) 557-0552,

Stage 5 front shocks: $2,089.99

Stage 5 rear shock: $1,499.99

FASST COMPANY: (877) 306-1801,

14-degree Quad Low Flexx handlebar: $399.99

YFZ rear brake clevis: $44.99

8mm rear brake return spring: $19.99

Metallic gray bar pad cover: $10

FASTHEADS: (435) 668-7776,

Yamaha Titanium valve package: $799

FMF RACING: (310) 631-4363,

Full Factory 4.1 RCT anodized/carbon end cap: $799.99

FOURWERX CARBON:(262) 501-9696,

Carbon fiber frame guard set: $90

Carbon fiber rear number plate: $65


YFZ intake system w/ airbox AIS block off plate: $343

GBC MOTORSPORTS: (800) 946-9241,

Mini Master 4-ply (size 20×6-10): $77.06 ea.

Mini Master 4-ply (size 18×10-8): $107.14 ea.

GLANN INNOVATIONS: (515) 528-9056,

Case saver: $80

Chain slide: $60


Victory Box Kit-4 w/ black aluminum bead rings: $599.44

HINSON RACING: (909) 946-2942,

Complete conventional clutch kit: $1106.99

HOT CAMS: (515) 402-8000,

Stage 2 intake camshaft: $208.01

Stage 2 exhaust camshaft: $208.01

LONESTAR RACING: (480) 834-2990,

E-brake block-off plate: $16

MAXIMA RACING OILS: 800) 345-8761,

1.45 Liters of Syn Blend Ester (2L bottles) – 10W-40: $10.99

Coolanol (64 oz., 1 bottle): $16.99

Racing DOT4 brake fluid (2 bottles for the quad): $17.99 per bottle.

ChainGuard: $11.99 (12 oz.)

FFT: $7.99 (8 oz.)

OURY GRIPS: (801) 229-9099, 

Single-compound waffle black: $11.99

PRO DESIGN RACING: (714) 534-0620,

ATV kill switch: $44.95

POWERMADD: (651) 462-8465,

Sentinel handguards (black/charcoal): $40

Sentinel ATV mount kit: $45

RATH RACING: (320) 234-7223,

Front bumper: $139.95

Rear grab bar: $87.95

Competition nerf bar: $501.95

ROCKY MOUNTAIN ATV/MC: (800) 336-5437,

CV4 radiator hoses: $74.99

ROLL DESIGN: (760) 731-5920,

Lobo II long travel control arms (MX/desert/dunes): $1595

RPM: (928) 771-9363,

Dominator II axle: $409.99

SSI DECALS: (877) 955-7446,

Custom kit: $199.95

STREAMLINE BRAKES: (909)-987-4213,

ATV front brake lines (+1” 2 line kit, color: smoke): $71.99

ATV rear brake line: $32.99

SUNSTAR: (937) 704-1462,

520XTG-100 Works chain: $95.95

Powerdrive 520-14T countershaft sprocket: $23.95

Rear 520-38T steel sprocket: $34.95

Non-round fixed disc front: $101.90

Non-round fixed disc rear: $101.90

TEIXEIRA TECH: (209)-833-9160, www.teixeiratech-com

MX linkage: $154

TIRE BLOCKS: (253) 973-5111,

20×6-10 kit: $75 a tire

18×10-8 kit: $120 a tire

TWIN AIR: (800) 749-2890, 

Backfire air filter for Power Flow: $52.95

WORKS CONNECTION: (530) 642-9488,

Engine plug kit: $39.95

Clutch perch: $183.35

Tach/hour meter: $44.95

WALSH RACECRAFT: (386) 364-4942,

Linkage mount reinforcement bracket: $149.99

Swingarm pivot bolt: $90

YFZ450R front axles: $149.99

Lowered subframe: $699.99

Footage studs (for Rath pegs 1.125”): $199.99

ZIP RACING: +44 1189 731700,

Email: [email protected]

Lo-Boy Pro Top: $190.94

Lo-Boy high density seat foam: $115.39

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