2019 Off-Road Factory Racebikes—Jacob Argubright’s Kawasaki KX450

Argubright’s all-around racer

Jacob Argubright races on grass track.
While he’s best known as a top desert racer, many forget that Jacob Argubright is competent in other facets of the sport. The 2015 AMA West Hare Scrambles Regional Champion, he’s added the AMA West Region ISDE Qualifier Series to his schedule this year and plans to go to Portugal as a first-year member of the US team. Surprisingly, his Kawasaki KX450 Qualifier bike is also his desert bike.Mark Kariya

When you're living the privateer life, budgets get stretched a lot faster so you've got to make those dollars go further. A stark example of this is the number of bikes you can afford—for many, having a separate racebike and practice bike is taking that budget to the limit.

That’s certainly the case with Jacob Argubright, who’s been on all sides of the issue as he transitioned from minis to big bikes, from private individual to factory team to privately backed team and back to his own deal.

But it certainly doesn't seem to be hurting his results. The Off-road Support/TBT Racing Kawasaki rider has settled on the KX450 and finds that it works well for him in all of the different arenas he's competed in so far this year: Hare & Hound, Best in the Desert, and ISDE Qualifiers.

In such disparate disciplines, you’d think Argubright would opt for different settings in each, but he prefers the set-and-forget line of thought. It makes things easier—a big consideration when you’re running the entire program yourself, from marketing and sponsorships to testing/training/practice to race logistics and more—and with as many hours as he spends on the bike, he gets to know exactly how it’s going to react in any situation. Such predictability has numerous benefits, as he’s discovered.

We caught up with him at round 2 of the AMA West Region ISDE Qualifier Series where he went 2-1 over the two days to earn second overall to GasGas rider J.T. Baker (1-3) based on total time.

2019 KX450 ridden by Jacob Argubright.
The 2019 KX450 Argubright rides isn’t exceedingly different than stock. Tires, suspension, and a number of other carefully considered parts help make it a winning package under him.Mark Kariya

Argubright describes himself as a rider in transition: “I’ve been aggressive [in the past] and I’m trying to be more smooth, more fluid. I’ve been working with Ricky Dietrich and just trying to better my form and just be better [overall]—smoother in the turns, better riding style, just better. My race craft this year, I’ve been way more calm. I haven’t freaked out when someone passes me. I think that’s helped me not be on the ground. I’ve had one crash this year and it was [while] practicing—I was trying too hard to catch Ricky Dietrich while practicing and I was riding over my head and I endoed.”

Starting at the front, one notices the TBT Racing stickers on the fork legs. TBT is a longtime sponsor. Rev Designs provides the graphics package, which Argubright helped create through his 911 Designed project. “I wanted a specific look and feel, and I wanted to do it,” he says.

Argubright also relies on Galfer brake rotors—though they’re the same size as stock—and Goldentyre knobbies. “The [90/100-21 front] Fatty is their pride and joy,” Argubright notes. “It’s like an old 20-inch 756 Dunlop; that’s how it feels—the tire’s massive! [That] makes it really cushiony for rocks. I swear by those!”

To avoid flats, he runs Nitro Mousse foam inserts in but a Golden insert in front—“It’s a little bit bigger; it’s just what I was recommended.”

A BRP top triple clamp allows use of oversize handlebar mounts for the Fasst Company Flex bar. “[They’re] pretty normal Flexx bars; I don’t do anything to them.” But Argubright does stick A’ME’s [MX Clamp-On] grips at both ends.

Front wheel of Jacob Argubright's 2019 Kawasaki KX450.
TBT Racing has been a longtime Argubright sponsor. While he prefers his suspension on the soft side, it works for him. He’s also a huge proponent of the 90/100-21 Fatty by Goldentyre with Golden’s foam insert for the added cushion it provides.Mark Kariya

Acerbis hand guards deflect some of the brush to help protect his fingers. “I think I’ve only broken one pair [over the years]; they’re really nice.” Those guards also cover ARC levers, which he buys.

Desert racing demands a steering stabilizer and Argubright uses a Scotts. The mounting post, however, is from GPR Stabilizer, which he modified by bracing it. “It won’t bend because I actually had [a stock] bend on the Yamaha [I raced last year], but I had wadded. It was at [the Hare & Hound National at] El Centro [California] when I crashed off the bomb [while] practicing.”

Although a standard MX tank would be adequate for ISDE Qualifiers, Argubright kept his bike in desert trim with its 2.5-gallon, dry-break-equipped IMS tank. “I get good mileage out of it,” he points out. “I made 57 miles at Best in the Desert.”

He adds, “It keeps everything the same; I’m used to it. Why change it? It’s more work for me [if I do]. It doesn’t bother me.”

Argubright continues, “On the mapping [connector], I run the leaner one, the aggressive one so it makes it a little [snappier].” Premium unleaded pump gas is sufficient for this.

Aside from that, he runs a full FMF exhaust system including a spark arrestor. That’s it for engine mods. “I don’t do a thing. All my motor work goes through Kawasaki of Simi Valley, [California,] and they just put a stock piston in. It’s built that way; it works. I run Evans coolant and I have yet to lose any with a 1.8 [radiator] cap,” he declares. “I run Moto Hose [to replace the OEM coolant hoses]. They’re a thicker hose and they get rid of the ‘Y’ [connector]. I bought them; I’m not sponsored by them.” Argubright uses Works Connection covers for several engine plugs as well as the lever perches that allow the assemblies to rotate instead of break in the event of a crash.

In addition, he fills the engine with more Maxima oil than is called for. “They recommend 700 to 800cc. We just run a full liter—a little bit more oil for the clutch. The clutch, it’ll squeal if the oil’s old. It’s a Kawi thing, so we run just a little more oil to fix that.”

Rear wheel of Jacob Argubright's 2019 Kawasaki KX450.
In Idaho, Argubright used a 2012 rear wheel simply because it was handy and already had the older, smaller 240mm rotor. He uses the smaller one because “sharkfins” for the larger new rotors aren’t commonly available yet. Goldentyre’s GT333 with a Nitro Mousse foam insert is his universal choice.Mark Kariya

Argubright runs Hinson plates in the OEM clutch basket. “The plates are a little bit better [than stock].”

Seat Concepts provides the cover for the saddle. “It’s grippier and it doesn’t give me a rash! It’s a good compromise between comfort and grip,” he says. Grip and durability are also why he chooses IMS Core footpegs. However, he runs a solid bolt instead of the sleeved pin of the stock setup.

Argubright also points out, “These aluminum [footpeg] mounts are really soft. I’ve gone through them every 20 hours; they’ll get ‘egged’ out, so Motion Pro is actually making some—and I’m going to test them soon—that’s a harder aluminum. That’s the only weak spot I’ve had.”

Jacob Argubright's O-ring chain linking the 13/47 DDC sprocket combination.
An O-ring chain links the 13/47 DDC sprocket combination, which he uses in all but the fastest races where he’ll switch to a 45. In that case, he also adds a link, letting him run the axle all the way back for the longest wheelbase possible, providing more stability.Mark Kariya

While the shock body is standard KYB, TBT revalves and resprings it for Argubright’s preferences, just like the fork. “People always say it’s a little soft, how it looks under me,” he admits. “I know it’s soft and I’m okay with that because it allows me to feel the ground really well and turn and hit rocks. I just know my strongest point is not the big whoops and elevation changes, and I’m aware of that and that’s okay.

“The only suspension changes I’ve made all this year [is preload in back]. I leave my forks in the same position [in the triple clamps]; I just move the rear [wheel]. When I go to Lucerne [Valley, California,] or a faster race, I move it back [by adding a link to the chain], which makes the bike longer which makes it more stable, but it gives it a different feel. Here [at the Qualifier] and pretty much everywhere [else], I’ll run it shorter, which makes it turn better. I like the feeling.”

He continues, “For gearing I run a 13/47 [with DDC sprockets]. I would run a 14, but with the big O-ring chain [I run], I’m worried it would hit the clutch slave [cylinder] so I just run a 13/47 pretty much everywhere. For the Mint [400] or Vegas to Reno or anything like that, I’ll add a link and put a 45 on. That’ll put [the axle] all the way back.” TM Designworks provides the chain guide, swingarm protectors, and skid plate. Homemade wire mesh screens help protect the radiators from desert brush.

IMS cell, Seat Concepts saddle, Fasst Company Flexx handlebar, A’ME grips, and Scotts steering stabilizer with a modified GPR Stabilizer mounting post.
Even though its added capacity (and quick-fill capability) isn’t needed in a Qualifier, Argubright didn’t switch to the stock MX tank. He’s used to the slightly larger IMS cell and why add more work? Also seen here are the Seat Concepts saddle, Fasst Company Flexx handlebar, A’ME grips, and Scotts steering stabilizer with a modified GPR Stabilizer mounting post.Mark Kariya

The rear tire is a [120/100-18] Goldentyre GT333. “It’s also good; it’s a pretty big tire. I run [Nitro Mousse’s] standard [insert] in the rear, but I’ve been testing—which I’ll be running [this weekend at the Qualifier]—it’s going to be called their Platinum, which is their medium compound which will be their new standard. It’s gray in color and it’s actually a pound lighter.”

Argubright runs a 2018-size (240mm) rear rotor instead of the 2019’s 250mm disc and explains, “Not too many people make a ‘sharkfin’ (rotor guard) for the new ones, so I run a Scotts sharkfin and I run a 240mm disc. I’m actually also running a 2012 wheel from my old Kawi,” he laughs. “I just happened to have an old 2012 wheel [laying around instead of relacing a new one with an 18-inch rim]—same rear axle, same brake, same everything.”

Argubright sums up his build: “My bike is really…it’s between bling and minimal. It’s just the necessary stuff that are really good parts. I take pride in checking everything and doing really regular maintenance. Like my racebike, I did a top end at 25 hours. Everything looks good; just keep everything tight.

“I’ve really tried not to change too much from what I like. I did one day of suspension testing and I haven’t changed it all year; I may change it a little bit toward the end of the year, but if you keep everything the same, you know what it’s going to do.

“I don’t have a lot of resources, so it’s me doing everything and I’ll always try to use the same stuff [everywhere], like I only run those tires. I’ve run the same [model] tires the whole year—haven’t changed it. The more choices, the more stress. The tire works pretty much great everywhere. In a couple spots [where] it doesn’t, I know what it’s going to do, so I think that helps me a lot.

“Consistency in training, consistency on the bike—I think that’s really kind of paid off.”