Published on March 9th, 2024 | by Joe
HMF YFZ450R Cross-country Racer Project Test Review
Known for making power, HMF has become much more than an exhaust company. Along with offering a broad line of the most customizable exhausts on the market with fuel tuning solutions to match, HMF offers a line of hard parts for popular sport ATVs improving appearance, protection, functionality and control. They asked if we would be interested in showcasing their full line of American made ATV products for the Yamaha YFZ450R, and we were happy to oblige.
In our previous episode, we freshened up Evan Hartzel’s OXCR Expert Class points leading race quad with a full round or hard parts and exhaust from HMF with which to finish up the 2022 season. We also installed a set of GPS beadlock wheels and larger GBC Ground Buster III tires for testing. It then received a fresh new look from FTP Powersports. Now we’ll put the HMF YFZ450R to the test on the cross-country race course at East Fork MX in New Vienna, Ohio; a track where Evan is known for winning.
The Machine
Evan’s 2014 YFZ450R came into this project with Houser long-travel A-Arms, Custom Axis front shocks with a BNR Motorsports revalved rear shock. An RPM Dominator II Axle is used out back, regarded by more pros through the decades as the strongest axle on the market. A Precision Racing steering stabilizer is another product you’ll find on almost every machine on pro row, along with Fasst Company Flexx Handlebars for their ability to reduce rider fatigue. Powermadd handguards help protect your hands from branches, flying mud, and debris. ODI lock-on grips are plush and stay put regardless of conditions. The seat is held more securely in place with 38 Motorsports seat pins, and the seat is covered in a Jet Trim cover that pairs beautifully with FTR Powersports graphics.
Young’s Cycleworx keeps this engine running strong and reliably although relatively, stock utilizing a stock compression Wiesco piston. A Raw Connections Race Harness cleans up the wiring harness. An Antigravity battery shaves weight and provides plenty of juice for quick starts. The clutch was switched out to a 2009-2013 setup for durability.
An aftermarket ECU is the most powerful tuning device available for modern four-strokes. This machine features a Vortex ECU custom tuned by BNR Motorsports. Evan retains a stock airbox and intake with a Pro Design Pro Flow Kit providing a more secure clamp-on style filter while allowing use of the stock airbox lid in wet races.
Strength is the primary reason Sunstar XTG 520 Chains are another product used by a lot of pro GNCC racers. It’s paired with a Sunstar chromoly Power drive front sprocket and steel rear sprocket running stock YFZ450R gearing. Rotors and Pads from Braking, provide the strong reliable stopping power needed for cross country racing.
With a proven winning race program throughout the early and mid-season, all of these items were retained, with other stock or aftermarket items replaced for this build.
Upgrades
HMF Performance Series Exhaust
At the heart of this HMF YFZ450R Cross-country Racer build is HMF’s Performance Series full exhaust system. It’s claimed to pick up 6hp and 4ft-lbs off torque over stock.
HMF original exhaust series, the Performance Series, features a stainless steel head and mid-pipe with mounts for the stock heat shield on the header. The silencer features a 4” aluminum shell with a 2 1/8” core featuring a special hole pattern that allows the exhaust to better disperse power gains throughout the RPM range. The Performance series puts out around 100-105 db of sound with an optional quiet core reducing sound output by 3-6 db. A spark arrestor is included that we shelved for racing.
The most customizable exhaust on the market we’ve seen, the silencer body can be ordered with a round or elliptical shape. It is available in a brushed aluminum finish or powder-coated a number of colors. There are different end-cap styles. Both the end cap, head, and mid-pipe can be blacked out in heat and stain resistant black ceramic coating that helps dissipate heat.
A Vortex ECU with custom tuning from BNR Motorsports was used to deliver the needed increase in fuel for the HMF exhaust.
HMF Equipment adds protection and Control
The HMF Heel Guard Set for the Yamaha YFZ 450 R/X is said to blend lightweight construction and heavy-duty durability. Built from premium grade 1-1/4″ X .120″ aluminum, the set includes aluminum heel guard frames, steel footpegs, extra-rigid steel foot peg cages, and thick, tough looking, nylon nets (available in various colors). The Heel Guard Set installs directly to the stock mounting location.
Available for either Motocross or XC applications, which we’re running, HMF’s front bumper for the YFZ450R or X is built of premium grade .120” wall 6063 T52 aluminum. It greatly increases front-end protection compared to the stock front bumper. Feeling both light and rigid, fitment was perfect. The looped sides provide a much greater area to grab onto when lifting the front of the quad, which can be necessary in a jam in the woods. A built-in skid plate helps keep the front of the frame and skid plate from auguring into the ground or obstacles.
HMF’s grab bar is also made of premium grade .120” thick 6063 T52 aluminum. It feels light and strong as we’d expect from a premium quality U.S. made product. With so many racers choosing HMF, we would like to see the addition of a rear number plate mount; a built-in whip flag mount makes their grab bar a great option for trail riders and duners alike.
Sold separately, HMF’s headlight and taillight blocks are light, made of T6061 aluminum. They mount up to the stock light mounting locations covering the open area and wiring after the lights have been removed, helping keep debris out.
Used by names like Walker Fowler and Chris Borich, GPS Victory Lock beadlock wheels are certainly good enough for most any race build. They were constructed of a specially heat-treated 6061 aircraft aluminum material. Dual bolt patterns for both Yamaha and Honda, allow them to be switched from one ATV to another, great for ATV owners and dealers alike.
GPS’ Victory Lock wheels are available with either aluminum or carbon beadlock rings offered in a variety of colors. Dual beadlock rear wheels, like the ones featured on this machine, are often favored by GNCC racers for their extra security on rough, rutted woods’ tracks. GPS’ single beadlock Victory Lock wheels were used up front. A reinforced rolled inside lip adds strength. The 4+1 offset front wheels offer the correct width and lighter steering minimum bump feedback compared to wider offset options. You can order the wheels separately or all together in GPS’ Victory Box, which comes complete with mud plugs for all four wheels.
As we’ve seen at the GNCC’s Spring rains and sandy tracks lead to deep ruts at some races. This is also the case at East Fork, MX where we’re testing, so we decided to run GBC’s taller 22” front and 21” rear Ground Buster III tires instead of the typical 21” front 20” tire setup used for tracks with more shallow ruts.
The Test
After giving our machine its makeover from HMF, GBC, GPS, and FTR Powersports makeover, we headed to East Fork MX in New Vienna, Ohio to hit their cross-country track where Evan and his YFZ450R is already known for racing up wins. Of course, there would be no better judge of the machine’s performance than by Evan Hartzel himself.
The BNR tuned Vortex makes for a cold hearted starter. Take it to the starting line warmed up and the machine fires quickly providing the perfect crisp throttle response you’re after when paying for an aftermarket ECU.
The HMF Performance Series exhaust delivers a deep, punchy and pleasant four-stroke sound for spectators. It’s a race pipe, but inside the helmet, it’s not offensively loud, even though it’s a two-hour race. Paired with a Vortex ECU, the powerband was significantly broader than stock pulling harder at lower RPMs with no discernable sputtering or hesitation when you crack the throttle. This makes the YFZ450R a little easier to manage in tighter sections or lower traction conditions. Midrange power wake up is significantly improved making time on long steep climbs or powering out of turns. HMF’s Performance Series wakes up the top-end, allowing you to hold the gas on a little longer before shifting, which can make the difference on making a pass or not.
Overall, we’re very impressed with the fit, performance, and sweet sound of the HMF Performance Series exhaust.
The combination of the taller GBC, GB3 tires and GPS wheels proved to be an outstanding choice. The larger size of the 22” fronts and 21” GB3 Pro rears had the YFZ450R’s sprocket and rotor guards dragging noticeably less often in the deeply rutted sections of the XC track, allowing us to ride more aggressively with less concern for damaging the quad. With .190” wall aluminum on the inner and outer halves of the GPS wheels, we felt very confident beating on them mercilessly, in ruts or on jump landings. If we got a flat during a race, we’d expect the GPS wheels to get us to our pits or the finish line no problem.
We found ourselves running a slightly lower pressure than we’d typically run with 21” front and 20” rear GB3s due to taller tires’ added volume, finishing our testing with 5lbs front and 4 rear. The larger GB3s provided a slightly suppler ride over roots and rocks. We could have added a tooth or two to the rear sprocket to maximize engine performance with the larger, slightly heavier tire and wheel setup, but they seemed to have virtually no discernable negative impact on engine performance. Traction is all we could ask for from a cross-country tire hooking up well in loam or hardpack conditions, whether they’re wet or dry. The front end tracked very precisely and the back end hooked up or drifted as desired. Although taller tires raise the YFZ’s low center of gravity slightly, the impact on cornering speed in flat turns seemed pretty minimal, due in part, to their willingness to slide predictably. We’d definitely run this wheel and tire combination on deeply rutted trails for racing, or as a good all-around setup for the recreational rider on a 450cc machine or larger, looking for one tire and wheel setup that would work well year round in all conditions.
Of course, having an ATV with a dialed chassis and suspension, thanks to the Houser Racing A-Arms and Custom Axis front shocks , RPM Dominator II axle, and BNR revalved stock rear shock, allowed us to push the other parts we’re testing to a much higher level. Judging by rider feedback and the way the machine reacted to nasty roots and braking bumps, the chassis and suspension were working far better than stock. As we’ve known for nearly two decades, you can’t ride nearly as hard for as long a period of time without the addition of a Precision Racing Steering Stabilizer, which this machine benefits from. Fasst Company’s Flexx handlebars really help protect your hands and joints in the upper body from impacts not fully dampened by the suspension. They’re a big deal in cross-country racing for a reason, and a great upgrade for any ATV, making longer rides more enjoyable. The gripper Jet Trim seat cover looks good and pays bigger dividends the wetter and nastier the conditions get.
HMF’s heel guard and footpeg set feel very solid and secure under foot. The wide footpegs help disperse impacts on the bottoms of your feet, greatly appreciated at times when you frame out on a jump or log. Dual rows of sizable teeth, with kick-ups on the ends, keep your feet feeling secure on the pegs in dry or wet conditions. The netted heel guard design lets mud fall through while adding protection in case your foot slips off the back of the peg. Overall, we were very happy with their performance with our only complaint being that HMF doesn’t offer them for other popular sport ATV models.
Besides making the YFZ450R look smoother and more complete with the lights removed, post ride cleaning proved that HMF’s light block offs help keep mud out, easing cleaning a bit as we’d hoped.
Conclusion
Starting this build, Evan’s YFZ450R was looking a little ratty for a project machine. After some serious cleaning with Maxima Bio Wash, and a complete quad wrap from FTR Powersports we’d be proud lining this YFZ450R up at any cross-country race. The combination of the HMF exhaust and other bolt-on motor mods add sufficient power for most racers in the woods. The addition of HMF’s other hard parts, GBC’s championship winning Ground Buster III tires and GPS beadlock wheels make the YFZ450R nearly race ready. Add the mandatory steering stabilizer and Flexx handlebars, and you’ve got a YFZ450R capable of running at the local cross-country level.
Narrow up the chassis and dial in the shocks like this machine, and you’ll have a machine capable of racing at a pretty high level anywhere in the woods back East. This HMF YFZ450R is a great example of what can be done with the Yamaha for cross-country racing. After filming this test, Evan went on to clinch the OXCR Expert class championship. Guess next time we’ll have to do a pro class YFZ450R build.
Make sure to check out part one for the complete build
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