Since it’s introduction in 2021, Kawasaki’s KX450X has been one of our favorite off-road racers here on the west coast. While it lacks what more traditional off-road bikes have, it shines in what it truly is designed for — closed-course off-road competition. For GNCC racers on the East and NGPC racers on the West, the KX platform has what’s needed without any extra fluff. The 5-speed standard-ratio transmission has just enough gear on either end to be competitive and effective, the chassis and suspension is one of the more compliant and neutral options, and the motor comes tame and usable but can be built up with a few bits and pieces.
Being the KX is the least changed from the MX model, the lack of a skid plate, oversized fuel tank, and handguards leave a few bolt-ons needed right from the showroom floor for most riders and racers. And the kickstand? It’s not the prettiest or cleanest design we’ve seen, but it does hold the bike upright trailside when needed. For our purposes, we prefer to take it off and only use it when necessary since it’s larger and bulkier than we’d like. With a major overhaul taking place in 2024 with a new chassis, updated engine design, and new bodywork, there’s been a learning process with this bike but most all of our testers prefer it over the older generation bike. The smoother, tractable motor is more rider-friendly in true off-road terrain and is less prone to stalling and more acceptable of low RPM chugging and lugging. Likewise, the chassis is more agile and takes less effort to maneuver — something that’s a positive at times and a negative at times depending on the terrain and rider on hand. Without further adieu, here’s what we found works best for the new KX450X platform to go west-coast off-road racing.
Per usual, we only run products and modify things we see fit after spending hours upon hours on the stock platform. Nearly all of these pieces have a performance aspect to them, or are replacing worn stock components with a more durable part.
TCS Powersports handled the suspension duties with correct spring rates, a -3mm shock mod, and simple valving updates based on the stock setting, only beefed up with better bottoming control for our faster riders.Pro Circuti’s Ti-6 Exhaust System woke up the power tremendously on the KX. In stock trim, the Kawasaki is very smooth and tractable, but lacks excitement and our faster riders feel the want for “more power” to ride it smoother at lower RPMs and using smaller throttle openings at times. Compared to some other exhausts we’ve tried on the KX’s, the PC system is more aggressive overall being slightly harder hitting off idle and a quicker revving power delivery. We prefer to run the quiet insert in for more back pressure which boosts bottom end power and smoothens the delivery a touch, making it more ridable.Flexx Handlebars help dampen small bumps and increase comfort to the hands for us in a critical way in the longer off-road races. We’re running the 12* Moto Low bend with the red elastomers for just enough flex to get the benefits of running the handlebars but not too much to take away feel and precision from the bike.GPR Stabilizer’s V5D Pro Kit includes a top triple clamp and their latest stabilizer offering. We don’t particularly like the GPR top clamp on some bikes, but we feel it helps the KX tremendously with a smoother, more compliant front end feel and a slight increase in cornering precision over the stock upper triple clamp — a win win in our books. Like most bikes, the Kawi really benefits from having a stabilizer mounted up as it greatly reduces head shake at the high speeds we’re racing at.Fasst Company’s Impact Moto Peg provides a strong grip and more importantly reduces vibration on the KX. The green machine vibrates more than we’d like, especially at higher RPMs where it makes good power, so we were looking to reduce vibration in key areas and the Impact pegs did the trick.GUTS Racing’s Wing Seat is a piece that makes gripping and controlling the bike MUCH easier for myself (Trevor Hunter), adding grip with the material and ribs on top along with the all-important wings protruding out the sides of the seat where your legs grip.The Corner Coach is a staple on a lot of our race bikes and the KX450X is no different. It keeps us in the optimum riding position at all times and helps reduce upper body fatigue over our 2 hours races with something holding us in place under hard accelerations.IMS’ 2.8 Gallon tank allows us to go the distance on gas and get in and out of the pits in a hurry with their dry-break. The stock 1.6 gallon tank is capable of going 45-60 minutes on most tracks, but that can be pushing it in faster or sandier conditions.The motor is left nearly completely stock internally as it doesn’t need much to pep it up aside from the pipe.Hinson Racing sent us a Billetproof Clutch for durability purposes. We did have a clutch fiber break on us after several deep sand races in a row and nearly 30 hours on the plates. We’d recommend changing the stock plates every 10-20 hours (or sooner if you’re harder on clutches and feel it slipping) and running non-synthetic oil when using the stock system. Or for a piece of mind and added durability, Hinson provides quality and durable parts and is an easy choice here.DT-1 Filters’ Screenless Air Filter Cage and Domed Filter have a nice seal, allow for more airflow and a slight increase in power, and can handle a little more dirt before becoming clogged.We tested the Works Chassis Lab Engine Mounts & Hangers last year on the Kawi and really like the handling characteristics with the different options. On deeper sand races or when riding in soft dirt and hard throttle openings, we like the stiff upper hangers. On harder packed tracks with more edges, we like the Medium upper hangers seen here. The stiffer mounts have less squat and more real wheel connection when hard on the gas and hitting bigger, rounder bumps. The Medium mounts offer more comfort and lean angle traction up to medium throttle openings, but can cause the rear end to wallow under hard accelerations.The stiffer front bracket was preferred under all conditions for better front end feel and traction.Sunstar refreshed our drivetrain with a stock 13/50 gearing setup. For tighter racing and riding, we could go up to 13/52 to tighten the gear ratios and lower first and second gear. We also run a one-link longer chain to get the rear axle as far back as possible in the swingarm for added stability and a smoother shock feel. TM Designworks upgraded the flimsy stock chain guide and slider with their robust units that will outlast the bike itself. Bullet Proof Designs’ Swingarm Guard adds strength to the chain guide tab, something we experienced an issue with with one of our testers when racing a Hare & Hound last year.We’re still running this map in our ’25 KX as it produces a healthy amount of power. For 2025, Kawasaki widened the parameters on their ECU so we’ll continue to mess with mapping the stock ECU for more improvements, although we’re pretty happy with where we’re at right now. And no, we aren’t running a Vortex ECU nor do we think that’s absolutely necessary on this off-road bike.P3 Carbon Skid Plate has protected the undercarriage for over 60 hours on our last two KX’s and still looks and works like new!Bullet Proof Designs’ Rear Disc Guard is a simple but effective bolt-on to protect the rear rotor from damage against rocks.Fasst Co’s Peg Shields keep mud and debris from jamming inside the footpeg and sticking it upright. This simple piece is easy to mount and very useful when riding in rocks or mud.We’re running Maxxis Tires in the NGPC Series and stuff our tires with Airmousses. The newest MX tires from Maxxis are much more performance oritented than their older tire offerings and the 80/100-21 MX-IH front tire is our go-to tire for most races while we generally stick to the 110/100-18 MX-SI out back. The Airmousses are very light and handle quite well compared to some other mousse’s we’ve tried as of late, and we run a 140/100-18 mouusse in the rear for better durability and feel over the smaller 110/100-18 mousse they offer.Acerbis refreshed the look of the bike with a compelte plastic kit, handguards, and a white front disc guard to pay homage to the Team Green days in the 90’s and 2000’s.Backyard Designs killed it on the retro themed graphics for us. The BYD graphics are of very high quality, are cut well and easy to install with little to no bubbling or peeling. And tying it all together, Dubya USA relaced some wheels with classic silver hoops. Black rims are all the rage these days, but it’s nice to see some silver and for an off-road bike, the silver looks a lot better over time compared to black.
The KX450X platform is a strong one straight off the showroom floor. We haven’t had a single test rider hop on this bike in stock or modified trim and not like it, something that we couldn’t necessarily say about the old bike (even though most of our testers really liked that bike as well, just not all). Aside from a broken clutch plate on our 2024 model when we were pushing it a little far on engine time, we’ve had great luck with durability so far. Our 24-25 test bikes, as well as the bikes our testers have personally bought, have been nearly flawless and only a few small things have needed some attention. The stock chain guide is like butter and will bend or break very easily, so an aftermarket one should be on the short list of parts needed. Likewise, the front chain lip pad on the frame (which replaces the old chain roller) can fall off if you don’t pay attention to it. We now put some threadlock on ours and check the bolt nearly every ride just to be safe after we lost one early on.
If you are a racer, we highly encourage you to take a look at the Team Green Racer Rewards. Kawasaki has stepped up in a big way, offering a lot of contingency money to amateur racers and is a program that can and will pay off in buying a new Kawasaki to go racing. In a lot of the local and national off-road series’ here on the west coast, several racers who contend in the top five of their respective classes have made the switch to green to “make money” racing with as much as $1,000 on the line for an A class win. This same bike won the 25+ A National Championship in the AMA National Grand Prix Championship last year with several race wins throughout the year.
As we always say, we build bikes to work. We aren’t here to show off an entire parts catalogue and we aren’t afraid to run a stock part if we think it’s better. Every part on here makes a difference whether it’s for performance, durability, or both. But there isn’t a single part on here that’s just for show and that’s how we do it.
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