The point in throwing the 2014 450 motocrossers into a vat and pouring them into the off-road environment is…what’s the point? These machines are all serious track racers, and even the weakest—or, more to the point, least changed—has enough DNA to dominate a motocross course under the proper guidance. But, the reality is that few 450s are actually raced. More are ridden at practice tracks or used for play riding and exploring off-road.
With this mission statement of versatility, we require a bit more out of them than just ballistic power and suspension designed to flatten the biggest of leaps. Tractability and a broad powerband are key, resisting flameouts at lower speeds is mandatory, and suspension adjustability is crucial. The majority of these machines haven’t changed all that much since last year, and all need a little love to get them into a healthy off-road mindset.
We’ve decided to attack this year’s 450 motocrossers-gone-hybrid with revised criteria. They were all put through an incredible and violent test on our long test circuit, where hills, hack, rocks, ruts, sand whoops and erratic speed zones demanded the most out of the machines. We evaluated them as is, identified their priorities, and ended with the overall potential of the motocrosser as a do-it-all machine. To make all the 450 MXers legal for off-road use, we installed spark-arrested, slip-on exhausts from Bill’s Pipes, DR.D, FMF, Pro Circuit, Slasher and Yoshimura. We also installed handguards to protect our mitts from everything the trails had to throw at us. So here goes.

As is: The KTM 450SX-F is the overall powerhouse of the group, making stellar power from bottom to top and with enough muscle to make your eyes bulge. The hydraulic clutch offers a smooth feel and superb engagement ability. The brakes are intense, the cockpit modular and the feel throughout has evolved into normalcy (a hard-fought battle). And, it has electric start!
On the less-than-stunning side are the weight and the suspension action. There was nothing we could do about the tonnage with our pedestrian budget, but the suspension lacks suppleness, even on a motocross track, and flat recoils when pushed into an off-road arena.
Priorities: Suspension is key here. We’ve had excellent results with both Precision Concepts and Pro Circuit valving/spring combos. The Precision WP suspension mods target smoother initial travel, yet the suspension stays up in the stroke, resisting diving and squat, and aids in traction. Pro Circuit’s mods were similar, though our settings seemed more compliant initially and a little softer through the middle. Both take the big hits superbly and are must-do mods if you want the machine to have an appetite for a versatile world.
The fuel tank is decently sized at 1.98 gallons, though IMS has an excellent 3.1 tank, and the bike could use a skid plate. TM Designworks has a minimalist plate and a full-coverage unit that are ridiculously strong. Exhaust-wise, there is an internal screen, but it is not a legal spark arrestor. The stock exhaust is too loud for real off-road, and there are two systems that can cure this problem: the Pro Circuit  and the FMF 4.1. Both systems offer a header with a canister or module that helps with sound and enhance bottom power. The rear mufflers are spark legal and help knock off some of the crack that all MX machines suffer with. Thankfully, both the Pro Circuit and FMF pipes come in stainless steel, which is critical for life in the off-road world.
Potential: There is no doubt that the KTM 450SX-F sits at the top of the heap. Power, starting, brakes, quality parts and adjustability offset some suspension groans that are totally fixable. The big question is whether it’s at the top by itself.


As is: The 350 is the weakest of the motocrossers, mainly in bottom-to-mid zest. Still, it makes very substantial numbers from the upper mid to peak and, under the tutelage of a smaller pilot, will hold its own against any 450. Like its big brother, it has a hydraulic clutch that is superb both in feel and engagement. The brakes are substantial, and it has a button start.
Unfortunately, as with its larger sibling, the suspension is the weak link in its arsenal. The 350 feels lighter than the 450 (although in reality it is 236 pounds compared to 243). Being a five-speed hurts its versatility a little, and because it’s more of a hammer-it machine, gas mileage actually suffers. The 1.98-gallon tank is only adequate for off-road survival.
Priorities: As with the 450, we’ve had superb results with both Precision Concepts and Pro Circuit valving/spring combos. The Precision WP suspension mods target smoother initial travel, yet the suspension stays up in the stroke, resisting diving and squat, and aids in traction. Pro Circuit’s mods were similar, though our settings seemed more compliant initially and a little softer through the middle. Both take the big hits superbly and are must-do mods if you want the machine to have an appetite for a versatile world. We have realized a big gain with a steering damper. We have tested the Scotts unit extensively, and it helps plant the front wheel and makes the bike feel smoother at speed.
We have nothing but praise for the exhaust, as the stock Akrapovic header is Ti and well designed, and the back can is quiet enough for a motocrosser. For this test, we bolted on a Slasher exhaust that made it spark legal, but in no way is it off-road-friendly. It’s simply too loud, though the power gain on top improved over stock. Again, as with the 450, both Pro Circuit and FMF offer excellent rear systems, as do Yosh and DR/D. All have spark-legal capabilities. FMF and PC do it with the least racket, but none of them really help bottom power, which is where the 350 is the leanest.
Potential: A big chunk of our testers loved the 350 because they could ride it harder and for longer periods of time than any 450! If you’re sized right and have a little bank set aside for suspension work, this machine will easily double as a competent GNCC/GP racer.
As is: The 2014 KX450F has undergone minor changes since 2013, but kept the light, broad and very strong powerband. Adjustability is key with the KX450F, with four different triple-clamp bar-mount options, two different peg-mount options, and unlimited mapping configurations for power management at the click of a computer mouse. Clutch pull is the easiest of all the cable-actuated models, and the KX450F suspension retains the KYB air fork.
In stock trim, the Kawasaki’s suspension is on the soft side for MX, making it excel on the trails. The Kawasaki’s starting is the best among the kickstarter clan. On the demerit side, checking the air pressure is a hassle. The stock running gear (chain, sliders and guide) is weak, and it’s the loudest machine of the group by far!
Priorities: The stock chain won’t last long—and neither will the slider and guide. Get some TM Designworks units and then forget about them! As for the chain, we went with a DID O-ring, though we’ve had great results with the RK X-ring too. Checking the fork pressure is a pain, so we bolted on (and it took seconds!) some Works Connection pivoting EZ-fill units. They rotate out of the way and can be checked with ease. Plan to get a bigger bar after one good tipover. The feel of the stock Renthal is excellent, but longevity is limited. The grips were shelved in favor of bolt-on ODIs, and the bar (a bulge unit) also saw service.
As for the exhaust, we tested a new DR.D bolt-on. It helped relieve some of the irritating volume and made it SA legal. We still wanted it softer in the roar department and felt that the FMF MegaBomb 4.1 rear (spark arrestor installed) gave us the best power with the quietest voice. The stock tank is a 1.6-gallon unit and is barely big enough for a decent off-road loop. IMS, Clarke and Acerbis all make bigger tanks for the KX.
Potential: This machine’s super-easy starting, very plush fork and good stable manners keep it at the top of the food chain. The must-dos are subtle. The other big groan is dealing with off-road-legal exhaust mandates and our own criteria, which is making it quiet. There is a fix, but it’s a cubic-dollar stitch job.
As is: There are several areas where the Honda kicks some serious tail: suspension compliance, quiet power and machine manageability. Being the lightest machine in the group at 231 pounds enhances the flickability factor. The Honda feels light and fun. These are big pluses in the off-road world, where longer days of negotiating tough terrain will wear a pilot down. Also, fit with a KYB air fork, the Honda design has a new piston that keeps it higher in the stroke than the KX-F.
The low lights with the red machine center on the clutch, which lacks good engagement and feel. Fortunately, the machine has improved fuel-injection control, and this has helped bottom power and flame outs considerably. Unfortunately, the small tank will force any off-roader to carry fuel, and the wonderful dual pipes require a strong dollar commitment if you need to go spark-legal.
Priorities: Last year we switched the entire clutch out for a Hinson unit, and it really changed the appeal of the machine. But, it’s a costly update, so be prepared. We have a new Rekluse manual clutch coming that uses 11 plates rather than 9, softer springs, and proprietary drive plates. We hear it works great. For the test, we bolted on a new DR.D single rear exhaust, and it worked well, sawed off a pound and a half, and was spark arrestor-legal. Noise-wise, however, it added decibels, and this didn’t sit well. We know from last year that the FMF combo of a Mega Bomb 4.1 with spark arrestors can give it a big power gain and keep the noise in check.
Plan to replace the stock chain soon. We went with a Sunstar O-ring and rear sprocket—a 49-toother that helped for tighter terrain. The rear guide is decent, though we swapped it for a BRP unit that is stronger and resists bending much better than the stocker. The bike needs big bars and a more modular top clamp, so we went with Renthals and an Applied top piece. With the stock 1.6-gallon tank, you’ll need to go big if exploring is on your itinerary. IMS sells a 3.1-gallon unit that is excellent.
Potential: The weight and feel of the CRF almost make it worth the price of admission, but once you pencil in a new clutch, an exhaust system, bars and a tank, the price tag for off-road acceptability starts reaching the boiling point.
As is: For 2014, this machine received the most changes throughout the chassis, engine and nearly every other part of the machine, and these changes moved the needle in a positive direction. This also makes it tough to evaluate available mods since there hasn’t been sufficient time to develop them.
Power-wise, there have been sweeping changes, all for the best, though it’s still a bit lurchy and seems to be light in flywheel feel during roll-on. Suspension is excellent both fore and aft, so we would leave any changes here for last. It’s going to need a larger fuel cell, and we know IMS is working on one, but the good news is that the stocker is 2 gallons!
Priorities: Injectioneering has done wonders with the stock mapping, and their throttle-body mods have helped increase roll-on smoothness and pull throughout the powerband. We have also tested FMF’s new 4.1 exhaust system, and it, too, has helped to soothe and smooth the flow of boost. Both mods are huge pluses. Right now, we have a Stealthy 12-ounce flywheel coming, and since we have tested Paul Whibley’s GNCC machine and know how smooth and stall-free his powerband is, we believe this will be a boon.
Like most of the Asian machines, the Yamaha is not gifted with great running gear. The rear sprocket wears quickly, as does the chain. We went with SuperSprox for total durability, an RK X-ring chain and TM Designworks rear chainguide. Because the YZ comes with a Pro Taper bar and a changeable top triple clamp, no changes were needed. We did toss the grips in favor of Renthal half waffles, though.
Potential: Last year, the YZ did not rate that highly. This year, it has moved up. It starts easier, has wonderfully versatile suspension and only lacks a smooth, off-road power delivery. Here, Injectioneering, FMF and Stealthy all help.
As is: We pretty much hammered the Suzuki in the 450 MX shootout for its unchanged, below-average fork action and old-world power delivery. Still, it rated as one of the top handlers and was voted best in the cornering department. We also know that in the GNCC world, the RM-Z450 is still a threat, proven by Josh Strang’s gold medal at the ISDE where he raced an RM-Z450 for the first time in 2 1⁄2 years (he campaigns a KX450F in the GNCC).
While handling is its strength, the fork action is harsh, the power delivery throbby, and the trick aluminum fuel cell will barely tote the gas to finish a 45-minute moto. The Suzuki does come equipped with an O-ring chain, a fairly quiet straight-through muffler and a very low Renthal Fat Bar.
Priorities: According to Bones at Pro Circuit, the Suzuki Showa SSF (Single Side Function) fork is one of the best designs in the business and, although valved on the moon, is easily fixable. We know this for a fact, since Bones did our suspension last year, and it drew rave reviews. We’ve tested both the Pro Circuit T5 exhaust with the new resonance can and the FMF MegaBomb 4.1 (with spark arrestor), and both rate highly. The sound level of both is close (and quieter than stock), and while the PC unit is lower mid to top and the FMF is bottom to lower peak, they both smooth out the flow of power and add tractability.
An IMS fuel tank is a must and holds 2.6 gallons (1.6 is stock). We swapped out the stock chainguide for a TM Design plastic unit and exchanged the very low Renthal bar for a taller Flexx handlebar that helped cut a good chunk of hack out of the earth’s surface. 
Potential: Despite some glaring issues, the Suzuki RM-Z450 has incredible potential as an off-roader and is still a great choice for a racer, partly due to a very tractable and decel-heavy powerband that is manageable off-road, along with a good dose of handling etiquette

Comments are closed.