TWO-STROKE TUESDAY | 2004 KTM 250SX FULL MXA TEST

This is an  archived 2004 KTM 250SX MXA test from the November 2003 issue of Motocross Action Magazine. Get your MXA subscription today.

It’s no secret that we didn’t like this bike very much in 2003. It finished last in MXA’s 2003 250cc shootout. Don’t get us wrong, the KTM 250SX had some charms. It was light (219 pounds). It made beaucoup horsepower (49.9 horsepower). It had a powerful front brake (with cauliflower rotor). And, it was blessed with a marvelous clutch (hydraulic).

But, those charms couldn’t outweigh the blemishes. In no particular order MXA test riders didn’t like the seat height (too tall), the handlebar bend (too low), the powerband (too skewed to the top), the handling (too much like a shopping cart), the forks (too harsh) or the shock (too stiff on small bumps and too soft on big ones). All in all, it had too many toos.

Thus, we enter 2004 with trepidation. Can KTM keep the charms, but get rid of the blemishes?

2004 KTM 250SX engine

Q: IS THE ‘04 ENGINE FASTER THAN THE ‘03?

A: Faster? Yes. More powerful? No. But it is a lot more usable. This year it is broader and more linear. Last year it pumped out 49.9 horsepower, the most of any 250 two-stroke or 450 four-stroke, but, and this is the big but, it wasn’t a very good engine. This year it makes 47 ponies. Power is not as important as placement.

Q: HOW DOES THE ‘04 COMPARE TO THE ‘03 ENGINE?

A: The MXA wrecking crew worked long and hard on our 2003 KTM 250SX. We made five major changes to our ‘03 engine. (1) We added a flywheel weight. The extra weight torqued up the power pulses and put more oomph into the ground. (2) We removed the stock reed block and replaced it with either a VForce or aftermarket Boyesen Rad Valve (not the one that it came with). (3) The jetting was rich. We swapped the stock 50 pilot for a 48 and the 178 main for a 175. We set the air screw at 2-1/2 turns out. (4) The gear ratios were hampered by a major jump between second and third gear. We ended up going one smaller on the countershaft sprocket (13) and one smaller on the rear sprocket (49). It may sound like convoluted gearing, but it narrowed the gap without spinning second out too soon. (5) The best pipe for the 250SX is the Pro Circuit Jeremy McGrath replica pipe. It adds four more horses at 8700 rpm (and a lot of over-rev).

Q: WHAT DID KTM CHANGE ON THE ‘04 ENGINE?

A: Here’s the list. It might surprise you by how closely in mimics the changes we made to our ‘03. (1) They lessened the peak horsepower. Why less horsepower? They realized that a lot of horsepower isn’t better than the right kind of powerband. (2) They increased the inertia mass of the crankshaft (which we achieved in 2003 by adding weight to the flywheel). The heavier crank was actually a mid-season change on the ‘03 model, but only a handful of the heavy crank bikes made it to the USA. (3) KTM spec’ed a Moto Tassinari VForce reed cage as OEM equipment. (4) The jetting, which was rich last year was spot-on this year (thanks to a NOZG needle instead of last year’s N3GW and a leaner pilot).

2004 KTM 250SX engine

Q: DOES THE NEW ‘04 ENGINE RUN BETTER?

A: Yes and no. The power is better through the low-to-mid transition, but not on top. Unfortunately, the big gap between second and third downgrades whatever power the 250SX makes. Even though KTM changed the ‘04 gearing to closely mimic the 13-49 that we ran last year, their choice of a 13-50 forced the bike into third too soon. Faster test riders swapped to 13-48, while the majority opted to reinstall the trusty 49. The taller gearing allowed us to use second for acceleration and third for drive. Of course, we bolted on our trusty but rusty Jeremy McGrath exhaust pipe.

Apart from the minor gearing glitches, which really need an internal fix, there is little to complain about in the power department.

Q: WHAT ABOUT THE 250SX SUSPENSION?

A: KTM owns WP. If they didn’t we doubt that they would have suffered through the last few years of recalcitrant suspension settings. The 2004 stuff is better than the ‘03 stuff, but its not better than most Kayaba or Showa stuff.

2004 KTM 250SX forks

Forks: In 2003 we swapped the stock 0.42kg/mm forks springs for stiffer 0.44s and lowered the oil height from 90mm to 110mm. Guess what? That is exactly what KTM did for ‘04. We recommend checking the oil height. Our forks exhibited considerable mid-stroke harshness and when we checked the stock oil height it was 10mm higher than advertised. We lowered it back to 110mm (and took a little extra out for good measure) for a better overall feel.

As for settings, we ran the fork caps flush with the triple clamps, the compression 18 clicks out and the rebound on 19 clicks.

Shock: KTM put some overtime into the rear shock. They went to a softer, 7.2kg/mm, straight-rate shock spring. The position-sensitive PDS rod was lengthen by 17mm to kick the damping in sooner (plus they tapered the end of the rod to feed the damping in more progressively). The high-speed compression damping was lessened and the low-speed damping increased.

2004 KTM 250SX shock

Our main goal was to balance both ends (which translated into lowering the rear and raising the front). The rear shock works best with 105mm of sag, 17 out on low-speed, 2-1/2 out on high-speed and 26 out on rebound.
The bottom line is that KTM made some real world changes. The suspension on the KTM is improved, but they have work to do.

Q: HOW DOES THE KTM 250SX HANDLE?

A: This is the crucial question. Why is it so critical? Last year we hated the 2003 KTM 250SX chassis. It was the worst handling frame of 2003. It was twitchy. The front end darted, dived and castered all over the track. It had very little bite. At speed it exhibited considerable head shake and, in slow corners, it tucked under. It was not to our liking (although we could muster considerable hate).

2004 KTM 250SX

Did they fix it for 2004? Sort of. Sometimes the Austrians mystify us with their decision making. In 2002 the KTM 250SX had 20mm offset triple clamps. It had the rep as a lazy handling bike and most factory racers (and MXA test riders) ran 18mm offset triple clamps in 2002. So, for 2003 the Austrian engineers put 14mm triple clamps on the 250SX. Why? No one knows. It made no sense to go so far overboard. It was as if they were saying, “if you want less offset, we’ll give you a lot less offset.” Now, for 2004 they have returned to 20mm triple clamps. It has been a strange odyssey.

Q: IS THE NEW FORK OFFSET AN IMPROVEMENT?

A: Yes. There is no doubt that 20mm offset is better than 14mm offset (especially since the head angle was steepened between 2002 and 2003). Thus, the 2004 250SX is more accurate, stable and responsive than the 2003. We would be remiss if we didn’t say that 18mm offset would have made more sense. MXA tested 14mm, 16mm, 18mm and 20mm triple clamps on this frame—it responded best with 18s (which is probably why most KTM racers run that dimension).

2004 KTM 250SX triple clamps

Our biggest complaint centered on the chassis’ unhinged feeling. The front and back of the bike never seemed to be tracking the same line. This is most noticeable in corners. When the front turns, the rear doesn’t follow as much as it surrenders (after a fight).

Q: WHAT ABOUT THE RUBBER?

A: The M59 front and M70 rear tire combo is an odd choice. But, we must admit that we like these old school tires better than Bridgestone’s most recent offerings. What’s so odd about the tire selection? Most OEM tires are hard-to-intermediate tires. KTM’s combo is best suited to softer dirt (the M70 is a sand tire).

2004 KTM 250SX

Q: HOW DID THEY DO ON THE MXA SQUAWKS?

A: Do you remember the MXA test crew’s list of 2003 blemishes? How did KTM do on fixing that list?

Seat height: KTM’s brochure claims the bike is lower, but that claim seems to be based on the assumption that the softer shock spring will comply more to the rider’s weight than last year’s stiffer spring. We’d like the rear end to come down about 10mm more.

Handlebars: Last year KTM lowered the bars by 11mm. A mistake. This year they raised them by 12mm. A plus.

Powerband: It’s broader, easier to use and has a torquier feel (thanks to the crankshaft inertia).

Forks: The ‘04 spec is last year’s modified spec.

Shock: KTM went to a straight-rate spring and revalved the PDS shock for a suppler feel. It’s better.

Handling: The 20mm triple clamps are an improvement over the 14s.

Q: WHAT DID WE HATE?

A: The hate list:

(1) Turning radius: Give yourself a couple extra feet in the pits.

(2) Seat height: It’s still too tall.

(3) Side panels: We caught our boot on the left side panel constantly. Last year our boots pulled the air box cover open, but for 2004 KTM increased the interface between the fender and airbox so that even if a boot hooked on it the airbox would stay sealed.

(4) Number plates: KTM’s side number plates are perfect for Grand Prix motocross. Why? Because the FIM doesn’t require numbers on the side of bikes. That’s good because it is almost impossible to get normal size numbers on a KTM. The side panels are too small, too trapezoid and too goofy.

(5) Front brake: For some reason the front brake pulsed. Sometimes the lever was tight, sometimes it was loose. We bled it until we bled. Lever pressure remained inconsistent.

2004 KTM 250SX filter

Q: WHAT DID WE LIKE?

A: The like list:

(1) Handlebars: KTM’s come stock with oversize, crossbarless, aluminum, Renthal handlebars. And for ‘04 they raised the bar height by 12mm. A good move.

(2) Grips: KTM dropped their traditional Domino grips for two-tone, Dual-Compound Renthal grips.

(3) Airbox: We’ve always liked the idea behind KTM’s easy access airbox (and this year it has a larger volume and three-pin filter cage), but it doesn’t go back on as easy as it comes off.

(4) Clutch: We like Magura’s hydraulic clutch. The big change this year is a smaller hydraulic piston. It gets the same action out of less lever movement.

2004 KTM 250SX hydraulic clutch

Q: WHAT DO WE REALLY THINK?

We think that the 2004 KTM 250SX is a better KTM for KTM aficionados. The real question is whether or not KTM can sway Honda, Yamaha, Kawasaki and Suzuki buyers to the orange fold? They can. The KTM 125SX proves that, but, for us, the 250SX is a much harder sell. KTM made a quantum leap forward for 2004. Now they need to hop, skip and jump their way towards perfection.

 

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