This bike rated third in our ’03 125cc shootout (Jan. ’03), but it earned that rank on the strength of its mega motor. At any rpm a bit above idle, the 125 SX engine is fast and responsive, and its power comes through with a meaty, torquey feeling that pulls you out of turns and lofts you over jumps.On the other hand, any rider who was the right size for a 125 found the ergonomics a bit stretched out and the suspension almost firm enough to race with the girlfriend on the back. Brilliant standard-equipment levels and that superb engine, which is both powerful and easy to ride, kept the bike in the hunt. In addition to all the other detail improvements made to the 125 SX, KTM actually specified a suspension setup that works for light riders. For the first time heavier riders have to work at getting a stiff enough setting. But for a 125, that is definitely an improvement.Many of the suspension changes that KTM engineered into the ’04s were aimed at keeping the rear shock from transferring too much load onto the front of the chassis. The changes worked for a more balanced suspension but also made the handling lighter, more consistent and more precise. Overall, the chassis is a much better match for the magic motor.200 SX
Why a 200cc motocrosser? That’s a fair question, but there are good answers. The first is that KTM made its current fortune building bikes that have a pool of customers waiting who don’t see the bike they want out in dealership land. There are many small and light riders in the 125cc class who would like to also ride the 250cc class but aren’t comfortable with the weight or power of a full-blown 250cc two-stroke. And at the other end of the spectrum from those light young guns are vet and senior riders who used to love 125s but find them too much of a handicap for their run-what-ya’-brung age classes. A 125 has no hope of a decent start, but a 38-horsepower 200 has a shot.So if you fit any of these descriptions or are stricken with a sickness for light and powerful two-stroke motocrossers, the 200 SX is your prescription. The 200 engine is derived from the 200 M/XC off-road weapon, but don’t confuse the 200 SX with a mild-motored trail engine in an MX chassis. The 200 hits hard and strong in the mid then revs like a 125. It isn’t for the faint of heart or bashful of throttle, but it is big fun in a compact package.What’s New: 125/200 SX
• New pipe tuned for added mid-range and high rpm power.
• Moto Tassinari V-Force reed valve is standard.
If Dr. Jekyll was a motocrosser, the ’03 250 SX would have been his mascot. There has never been a production two-stroke 250 with a motor as downright gnarly. It hit hard and pulled strong to the tune of nearly 50 ponies—yikes! Its chassis wasn’t as well-mannered as the 125 SX’s, either. So for 2004, KTM spent the most time and effort on the 250 SX. It got the same chassis upgrades as its siblings, but its engine was treated to a dose of manners. The power is still potent but broader, smoother and more likely to be put to the track and not your elbow. Life is tough for the 250 SX. Not only does it have a packed class of stellar machines to compete with but it has to keep an eye on little brother 200 and big brother 450.What’s New: 250 SX
• More reliable clutch plates.
• Single-ring piston
• Lighter ignition cover.
• Exhaust port timing adjusted for smoother power delivery.
• Pipe and silencer redesigned for increased torque and more usable power.
• Crankshaft with increased rotating mass for better traction and more tractable power output.
• New carburetor setting for smoother power delivery.
• Moto Tassinari V-Force reed valve.
450 SX RFS
Motocross 450cc four-strokes are rapidly improving, and we love ‘em, but they are gaining some of the traits of 500cc two-stroke motocrossers. The class leaders are running right at 50 horses and have serious bark in the midrange. That bark and power are big fun while you are fresh, but there are riders who like the smooth, tractable feel of a more traditional four-stroke. Compared with older KTM four-stroke weaponry, the 450 is more snappy and quicker revving but goes without the midrange bite of the Honda or Yamaha meat eaters. For serious powermongers that may be a handicap, but for most of us the KTM is an easier, less tiring ride than the barkmasters.The 450 SX is slim and light feeling, with a chassis that is both nimble yet fairly relaxed at speed. Smaller riders aren’t dwarfed, but the four-position handlebar clamps allow a rider to fine-tune the riding position to suit a wide variety of body types. With the plusher suspension for ’04, it is in the hunt. And if you absolutely, positively have to have massive boost…What’s New: 450 SX RFS
• Lighter and improved valve springs and retainers for quicker revving and better reliability.525 SX RFS
There is the 525 SX. It is the undisputed powerhouse of four-stroke motocross, but even with massive boost available at virtually any rpm, the engine remains a willing and unpicky starter and, once rolling, has power so smooth as to seem docile. That is until you notice that berms are disappearing in your wake and you start to routinely overjump the biggest leaps at the track. You can work the more modest parts of the powerband to good effect and even keep the suspension more unloaded and free than you can with the 450 SX. The 450 also makes big power but asks more rpm in return. If you ever considered yourself an Open class fan, you’ll find the 525 gives you all the meat of a 500cc two-stroke but in a slim and modern package that is much easier to handle.What’s New: 525 SX RFS
• Digital control box raises redline to 9800 rpm.
• Crankshaft has more rotating mass (via removable weights) for more traction and less stalling.
• Single-tube exhaust and reshaped silencer as on ’03 450 SX.So what if you can’t race it in a supercross or AMA 250cc National any longer? There are plenty of classes to choose from at local races. Go ahead, grab more than your share of holeshots and enjoy yourself.Opinions
The KTM 125 SX has drastically different suspension. The rear shock is a lot better; it allows you to charge a lot harder down hills, and it drives through bumps instead of deflecting off them. The power is amazing. It hits really smooth but at the same time is very powerful. Overall, the 125 SX is a big improvement from last year. The 250 SX also has noticeable improvements. Its power is very different from last year. It generates more bottom, has a less rude transition to the mid-hit and still runs very strong on top. The suspension is completely different. It’s a lot plusher and handles way better. The ’04 is a big step up from ’03, but I think I’ll take a hard look at that 200 SX before I decide for the year.
Tyler Keefe/5’10″/160 lb/IntermediateThe 125 SX has lots of power–as usual. The suspension package impressed me most. Last year the 125 had some trouble with high-speed stability. This year the suspension is day-and-night improved. You can come into big braking bumps and not have that front-end dive. The rear of the bike actually squats now instead of standing up. The only problem I had was it was a little rich on the day I tested it. The 250 is equally as impressive. The suspension is by far better than ’03, and the motor is still strong. The thing I liked the most is that the motor is actually smoother this year, which gives it a forgiving feel. Instead of ripping your arms out of their sockets, it actually lets you hang on for more than four laps!The four-strokes are what I get really excited about! The 525 has so much power that you don’t want to get off it. Ease of riding and good suspension make it hard to sleep the night before you get to ride it. The 450 is fun also but does not produce as much power as its big brother. This year should be a good year for the orange crush.
Kris Keefer/5’11″/170 lb/ProFor years KTMs have suited me just fine, but I don’t wear orange glasses that blind me to the suspension problems of the past few years. I’ve had some modified bikes that work very well, but the ’04s feel as plush as any no-link KTM I’ve ridden. On top of that, the suspension improvements keep the shock from loading the front of the bike. The whole chassis feels more relaxed and balanced with more natural, intuitive handling. And that goes for all the models. As far as the engines go, I tend to like the ones at both ends. Both of the four-strokes are on my frequency, but the 525 produces the largest grins. I also love the 125 and 200. Both are light and zappy and handle great. Big fun! The new 250 SX is a major improvement, but for the 250cc class I also have a choice of the 200 or 450, so of the three I’d probably pick the 450. It feels like it has all the speed of the 250 but in a package I can ride more laps before I bonk.
Karel Kramer/6’1″/200 lb/Novice