Off-road bolt-on parts guru Jay Clark aims to make Kawasaki’s KX450F even better.
You wouldn’t think there’d be much that could be done to improve Kawasaki’s awesome KX450F. A shootout winner and Bike of the Year honoree over the past couple seasons, the big-bore KX thumps the competition with amazing power in an excellent chassis with suspension that is more than race-ready in stock form. So why try and mess with success?
If you are bike builder Jay Clark, the answer is twofold. First, it’s what he loves to do. Clark is a tech-head who has been building bikes, using the latest aftermarket parts, for over 20 years. If he thinks he can make a motorcycle, ATV or UTV faster, stronger, lighter or just prettier to look at, he’s game to try. Second, it’s his job. As the owner of Jay Clark Enterprises, Clark has a vast list of clients that he works with to showcase their latest bolt-on hardware. It’s kinda like giving a kid the keys to a candy store.
So when Clark got hold of a 2014 KX450, he cut loose on it in typical Jay Clark fashion, throwing every part he could find at the bike in an effort to make it better than the stocker. The fact that it is far more trick-looking is only a bonus.
However, if you read about our Project Hot Cams Suzuki RM-Z250, the first installment of three bikes that we will be showcasing with Clark’s handiwork, you already know that we are aware that some folks will look at bikes like this one as overkill—and that isn’t necessarily untrue. But like we have said, the purpose of this bike is to show the many opportunities a KX450F owner has to modify his or her bike. So maybe you’re a real animal and want more power out of your KX450F? There are mods on this bike that will help you to that end. Think the engine already makes enough power? Leave it alone and look at the suspension and other hard parts showcased here. You just want a graphics package that is more personal than the stock KX? Clark’s bike boasts a different look that should at least give you some good ideas.
And, as we said before, if you see a part here that strikes your fancy, shop around for it. The web is a powerful tool for bargain hunters, and sites such as Rocky Mountain ATV/MC usually offer parts at prices below retail because they get large-quantity price breaks, passing those savings on to the customer. Most often, sites like Rocky Mountain sell the same part for a lower price than the one for the same part on the manufacturer’s own website.
Engine
What do you do to make an already powerful engine even stronger? Clark started inside the KX450F, swapping the stock piston for a Vertex High Compression forged piston kit, which includes the piston, rings, wrist pin and clips. The Vertex piston bumps up the KX450F’s compression ratio over one point, taking it from 12.5:1 to 13.6:1. Increasing the compression will increase power, but that power comes at a trade-off, as you can forget about running 91-octane pump gasoline. Clark fuels his machines with Renegade Racing Fuels SX4, which is rated at 97 octane (R+M/2) with an oxygen content of 3.7% and a specific gravity of .740—you should check to make sure that this fuel is legal with your local race sanction before running it. We do know that Renegade Racing Fuels have a proven track record, as they are used by the GEICO Honda team. For more information, check out their site at www.renegadepro1.com.
Clark also swapped out the stock cams for a set of Hot Cams Stage 2 cams. Whereas Stage 1 cams are designed to increase power in the low-to-midrange, Stage 2 Cams are all about increasing mid-to-top-end torque and horsepower. Hot cams claims that the Stage 2 cams produce more power than the OE cams from 5000 rpm and up without sacrificing low-end power while also outperforming Hot Cams’ own Stage 1 cam set from 7000 rpm on up to redline.
To route the spent combustion charge out of the cylinder more efficiently, this KX450F uses a tried and true weapon in Clark’s arsenal, an FMF Racing Ti Megabomb header and Factory 4.1 RCT Ti muffler with carbon fiber cap. If the full-Ti and carbon systems are out of your budget, check out FMF’s website for more cost-effective systems constructed of less-exotic materials.
Clark left the Kawasaki’s excellent stock fuel-injection system alone, but out ahead of it is a Moto Tassinari’s AIR4ORCE intake boot, which comes with adjustable velocity stacks that allow the rider to alter the intake velocity to effect slight changes in power delivery. The airbox houses a Uni-Filter two-stage air filter for an extra measure of grit protection.
Hinson Racing has practically become a household name in the powersports industry, with a reputation for building practically grenade-proof clutch components, so Clark called on Hinson for one of its full Hinson FSC clutch and spring kit to give the KX clutch a little more holding power. He also added Hinson Racing clutch cover.
A CV4 formed silicone coolant hose kit gives the engine compartment a little more visual pizzazz. Clark also topped the radiator with one of CV4’s high-pressure radiator caps.
Suspension
To dial-in the KX450F’s suspension, Clark enlisted the services of Mike Battista at MB1 Suspension in Corona, California. Battista is a former Team Honda Showa suspension expert, who MB1 in 2004 to provide his suspension services to the public.
As you may know, the 2014 KX450F is fitted with a 48mm Kayaba Pneumatic Spring Fork (PSF), which uses compressed air instead of coil springs to hold the 450’s weight. Kawasaki went with the air spring design over conventional springs because they claim that it improves smoothness and enhances the fork’s ability to follow any kind of terrain, specifically high-speed bumps. Battista says that the PSF forks work extremely well when set up properly.
MB1 starts by installing its own PSF Fork pistons with a bushing instead of a band for less friction, and changes the damping to give it less “float” but more plushness to eliminate any harsh feeling at MB1’s recommended air pressure, which is usually 32-37psi. MB1 also recommends changing the fork oil every 12-15 hours of use for best performance and to avoid any failures or fork seals leaking, which can ruin your day. Out back, MB1 changes the shock piston to add more control during compression and rebound and to install a check valve nut to isolate the compression and rebound circuits from one another. Here are some baseline setting that MB1 recommends for its modified 2014 KXF450F fork and shock:
Fork
Compression: -12 clicks from full compression
Rebound: -9 clicks from full rebound
Fork position: 5mm
Oil level: 235cc
Spring Pressure: 35psi
Fork lockdown: 130mm
Shock
Spring: 5.5kg
High-speed compression: -2 from full compression
Low-speed compression: -10 from full compression
Rebound: -16 from full rebound
Sag: 100mm
Holeshot link: 130mm
This KX450F’s rear suspension features MB1’s Factory Linkage Arm and Holeshot Link device, developed in conjunction with some of the factory MXGP teams overseas. The Factory Linkage Arm features a longer pull rod that is intended to improving overall stability when entering corners. MB1 says that it is also designed to reduce rear end kicking and frontward weight pitch when the under heavy braking, such as when entering the first corner. The Factory Linkage arm is CNC-machined out of 7075 alloy and comes all ready to bolt on using the OE bearings and seals.
Accessories
Naturally, Clark fitted the KX450F with a host of cool accessories with good looks that match their functionality. Renthal supplied its 997 Twin Wall handlebar, Big Bar mounts and Dual Series grips. The stock gearing is retained, but power is transmitted to the rear wheel through a Renthal rear sprocket and Renthal R1 Works chain.
Practically identical to our earlier project RM-Z250, the KX450F features a Tusk Off-Road Impact wheel kit, with nice-looking, blue-anodized hubs. Up front, a Tusk Off-Road Typhoon 270mm oversized floating rotor kit supplies more braking force than the stock 250mm unit. Clark also swapped the stock rear rotor for a Typhoon stainless steel rear brake rotor. Clark used his Dunlop connection to land a pair of the company’s new MX52 tires, which are recommended for intermediate-hard surfaces.
Works Connection is also one of Clark’s go-to companies, and this KX450F sports a number of WC items, including Elite lever perches, a Works Connection front-end holeshot device, anodized axle adjuster blocks, anodized front and rear brake reservoir caps, air-fork EZ-fill cap set, hour meter and titanium footpegs.
And what would all of the trick parts on this bike be without an eye-blazing graphic scheme to help draw attention to them. For that, Clark turned to Cycra Racing for a full set of its Powerflow bodywork, which is adorned with Decal Works Semi-custom graphics. Topping it off is a Moto Seat Two-Tone seat cover, which boasts a material that is claimed to offer more traction than the stock cover.
Riding Impression
Juggling multiple bikes out at Southern California’s Competitive Edge Raceway gave us far less time to sort out the KX450F for our test rider Ryan Abbatoye than we would have liked, but we did come away with some interesting impressions.
First, we would wholeheartedly recommend the powertrain mods for fast Intermediates and Expert riders, as the piston, cam and exhaust combination really wake up the big Kawi. Thanks to its already excellent stock fuel-injection, the KX exhibited sharp throttle response, and its mid-range and top-end power are improved by Clark’s mods, giving it a more potent midrange and a screaming top-end. Abbatoye really seemed to enjoy holding the gears longer and revving out the motor more like a 250 than a 450.
As for the suspension, all we can say is that we wish we would have had more time to sort it out. MB1’s reputation is strong in the business, and it would have been great to have Battista or one of his engineers along with us to help us sort it out within our extremely limited timeframe. We certainly wouldn’t let our issues keep us from calling on MB1 in the future if we are in need of custom-tailored suspension work.
On the plus side, we did spend enough time playing with the MB1 Holeshot Link to determine that it’s a pretty nifty unit. Activating both the front and rear holeshot devices at the same time really hunkers down the big KX, making it easier to control during a hard launch. With the Holeshot Link, the KX resisted wheelying, which allowed Abbatoye to drive forward at full throttle. The system deactivates when the rear suspension hits a decent bump-we had no issues with it sticking or keeping the rear end locked down for too long a period off the start.
Regardless, if you’re looking for ways to modify or replace parts on your stock KX450F, all of the items on this particular machine are worth a look. The only limiting factor is how far your imagination—or your wallet—can take you.
2014 Vertex Kawasaki KX450F Project Parts List
Vertex Pistons www.vertexpistons.com, 515-270-2302
Replica Forged High Compression Piston kit, $265.23
Hot Cams www.rockymountainatvmc.com, 800-336-5437
Stage 2 Intake Cam, $179.95
Stage 2 Exhaust Cam, $179.95
FMF Racing www.rockymountainatvmc.com, 800-336-5437 800-336-5437
Factory 4.1 RCT Ti Muffler w/carbon cap, $549.99
Ti Megabomb header, $349.99
MotoTassinari www.rockymountainatvmc.com, 800-336-5437
Air4orce air boot, $298
Uni Filter www.rockymountainatvmc.com, 800-336-5437
RM-Z250 Air Filter, $30.95
CV4 www.cv4.net, 800-874-1223
Formed Silicone Coolant hose kit, $139.62
High pressure radiator cap, $22.73
Hinson Clutch Components www.hinsonracing.com, 909-946-2942
FSC clutch plate & spring kit, $199.99
Billetproof clutch cover, $169.99
MB1 Suspension www.mb1suspension.com, 951-371-5045
Fork Revalve, $180
Fork Oil, $24.99/qt. (two quarts required)
Fork Midvalve PSF Piston and shim kit, $179.99
Fork Pump, $69
Shock Revalve, $180
Shock Oil, $24.99
Shock Piston and shim kit, $179.99
Check Valve Shaft nut, $79.99
Shock Lowering washer 2mm, $35
Rear Link Holeshot Device, $399
Renthal www.renthal.com, 877-736-8425
Rear sprocket, $69.95
R1 Works Chain, $85.95
997 Twin Wall Handlebar, $199.95
Dual Series grips, $15.95
Big bar Mounts, $59.95
Works Connection www.worksconnection.com, 800-895-8292
Elite Perch, $79.95 each
Front brake cap, $27.50
Rear Brake cap, $24.95
Axle blocks, $49.95
Hour meter, $39.95
Hour meter mount, $14.95
Ti Footpegs, $219.95
Air Fork EZ Fill, $99.95 (pair)
Pro Launch Holeshot Device, $109.95
Tusk Off-Road www.rockymountainatvmc.com, 800-336-5437
Typhoon 270mm oversized floating rotor kit, $149.99
Typhoon stainless steel rear brake rotor, $99.99
Impact complete front/rear wheel kit, $729.99
Dunlop Tire www.dunlopmotorcycle.com, 800-845-8378
MX 52 front 80/100-21, $120.89
MX 52 rear 110/90-19, $134.04-149.25
Cycra Racing www.cycraracing.com, 336-472-2242
Powerflow Body Kit, $169.95
DeCal Works www.decalmx.com, 815-784-4000
Semi-Custom Graphics kit w/pre-printed numberplates, $269.90
Moto Seat www.motoseat.com, 951-258-5229
Two-Tone seat cover, $49.95
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