MXA’S 2006 KTM 250SXF TEST

Motocrossers like to think of themselves as individuals. They believe that they are unique in a world of brown shoes and starched shirts. They want to stand out in a milquetoast world of followers with their bravado, creativity and oneness. In a society rife with conspicuous consumption, subliminal marketing and mass production, racers value their uniqueness above all else. Unfortunately, society doesn’t reward strangenessit punishes it; labels it as cultish; and abuses it by derision. The same holds true for a product that tries to break the moldeven in the world of motocross bikes.

 

The KTM 250SXF is a stand-alone product. Its designers didn’t drink from the same trough as the KX-F, RM-Z, YZ-F or CRF engineers. They didn’t attend the same technical schools, worship at the altar of Soichiro, or command their thought patterns to stay in the box. The KTM 250SXF is a unique motorcycle. And you would think that in a world inhabited by wannabe rebels, it would be lauded for its anarchist ways. Not so. In the larger sense, motocross racers, for all their anti-hero posing, want to ride the same bike that everyone else rides. There is comfort in familiarity. There is comfort in numbers. If 10,000 people buy a CRF250, the thinking is that they must know somethingeven if it’s just that a large number of people made the same decision.

 

The best thing about KTM is its uniqueness. It isn’t a clone-mobile. KTM’s engineers looked at the same goal perimeters as their Japanese counterparts, but came to different conclusions. That’s admirable. The worst thing about KTM is their bikes’s uniqueness. They do things so differently that their product assaults the senses. KTM’s machine asks you to take a leap of faith, to step beyond your comfort zone and believe that there is another waythe Austrian way.

 

Q: WHAT’S SO UNIQUE ABOUT THE KTM 250SXF?

 

A: Make no mistake about it, this is not Xerox engineering. The 250SXF is a totally unique machine. There is nothing borrowed and nothing blue (or red, green or yellow).

 

Q: WHAT DESIGN FEATURES ARE UNIQUE TO KTM?

           

A:  Let us count the ways.

(1) Rear suspension: The single-side, single-shock, no-linkage rear suspension system uses an Ohlins-licensed, Dutch-built WP shock with two pistons.

(2) Frame: In a world of aluminum, KTM has stuck with a steel tube chassis, albeit oval.

(3) Valve train: The four valves don’t ride on buckets or teeter-totter on rocker arms. Instead, the cams engage what KTM calls “finger levers” that push directly on the valve stems.

(4) Cam chain: The 250SXF cam chain tensioner is powered by bleed from the oil pumpwhich pressurizes it hydraulically.

(5) Spark plug: KTM’s spark plug extends out the left side of the cylinder head so it can be removed without taking the gas tank off.

(6) Transmission: It’s a six-speed. The only other six-speeder in the sport is the Yamaha YZ125 two-stroke.

(7) Gas cap: Instead of a screw-on gas cap, KTM doubled the size of their old cap and made it an aviation-style, quarter-turn cap.

(8) Triple clamps: KTM’s CNC-machined-billet triple clamps can be changed from 20mm offset to 18mm offset by rotating the steerer tube.

(9) Swingarm: Look at it closely, because it is one piece of aluminum. No welds. No joints. No bonding. No seams. The swingarm is cast with internal gusseting that eliminates any unequal flex.

 

Q: HOW DIFFERENT IS THE 2006 KTM 250SXF FROM THE 2005-1/2 KTM 250SXF?

           

A: The MXA test crew wasn’t expecting a world of difference between this year’s 250XF and last year’s; after all, the 2005 model wasn’t even in the States until June 1, 2005. But, there is a small cadre of changes.

(1) Rear shock: The separation between the working areas of the two pistons in the WP shock has been made less restrictive. The shock also gets a larger bump rubber and new valving.

(2) Rear master cylinder: KTM was concerned about the life of the master cylinder seals. For ?06 they installed new seals and chamfered the passageways for less tearing.

(3) Front master cylinder: The leverage on the piston has been increased, thanks to leverage from the lever.

(4) WP forks: KTM tried to improve initial fork movement by using low-friction bushings, slippery coatings on the stanchion tubes and revised tapers on the fork leg. The valving has also been changed.

(5) Oil mister: KTM’s engineers moved the oil mister on the center cases to redirect the oil mist onto the piston.

(6) Valve guides/springs: New material has been used for the valve guides, and valve springs are spec’ed from a new supplier.

 

Q: HOW FAST IS THE 2006 KTM 250SXF?

 

A: We like this engine. It is very fast in a very sneaky way. Unlike the YZ-F, KX-F, RM-Z or CRF, the KTM 250SXF churns out its power. It produces its power much lower in the range than its competition, and it feels more like a small 450 than a big 125. It is the only 250 thumper that actually “thumps.”

The rev limiter, which is really just retard, is set at a lofty 13,500 rpm (about the same as the other 250cc four-strokes), but let’s not get too excited about getting it into dog-howling range. Although the 250SXF will get to the rev limiter, it isn’t fast up there. It flattens on top. It is best to short-shift the KTM and depend on its abundant midrange to get the job done.

 

Q: HOW DOES THE KTM 250SXF ENGINE COMPARE TO THE COMPETITION?

 

A: It’s got a very chuggy feel that is almost effortless to use. This bike makes its best power on the torque peaknot at the top of the horsepower curve. If you shift at max torque, you will be rewarded. If you rev it, you will be punished. Almost every MXA test rider described the KTM 250SXF as a “mini-450.” The 250SXF’s power profile mimics a 450 powerband more than the typical rev-it-to-the-moon 250 four-stroke.

 

Q: WHAT DID WE THINK OF THE STOCK GEARING?

 

A: It’s too tall for a six-speed gearbox. The benefit of one extra gear is that the gaps between first through sixth can be fine tuned to suit track conditions. We swapped the stock 48-tooth rear for a 49. This brought third gear into play sooner.

 

Q: WHAT’S THE STORY BEHIND THE NO-LINK REAR SUSPENSION?

 

A: Yes, Virginia, it is different, but don’t fret about the lack of shock linkage. In a technical sense, a rising rate linkage is not necessary. By positioning the shock within the known framework of a scalene triangle (one in which the sides have different lengths and angles), it is possible to duplicate the rising rate of any linkage system (since the triangle changes as the rear wheel moves). Although the MXA wrecking crew has some doubts about the rising rate that KTM chose (as does independent designer Horst Leitner, who built KTM’s first no-link prototype), the single-sided, single-shock, no-link system is nothing to be afraid of, as Nathan Ramsey, Josh Hansen and Mike Alessi proved on the AMA circuit.

 

The WP shock features two damping pistons (instead of one). One piston is speed-sensitive (to the velocity of the oil rushing through it). The second piston is position-sensitive (to the location of the shock shaft). How does the WP shock know which piston to listen to? A tapered rod runs through the shock shaft, and that rod activates both pistons by cutting off bleed-by through the shock shaft (prior to halfway, only the speed-sensitive piston is operational).

 

Q: HOW GOOD IS THE SUSPENSION ON THE KTM 250SXF?

 

A: Thanks to some stiffening of the frame around the swingarm pivot and new valving specs, the 250SXF suspension is the best stuff that KTM has ever offered.

 

Forks: Last year, KTM released about 350 250SXF’s in the United States. The 48mm WP forks on the limited-edition 2005 model, which was really a pre-release of the 2006 model to circumvent AMA Pro Racing rules, were very harsh in the midstroke. So harsh that every test rider insisted that the forks needed to be revalved. Instead, we lowered the oil height by 15mm and were rewarded with a very plush and responsive set of forks.

 

Oil height is a cheap, easy and very effective mod for KTM owners. Our best fork setting was 22 out on compression and 22 out on rebound.

 

Shock: Step one of any KTM suspension setup program is to slide the forks down in the clamps until they are flush with the top triple clamp (which we rotated from 20mm to 18mm offset to increase trail and lessen front-end wag). On the shock, we opted for 103mm of race sag and set the clickers at 18 out on the low-speed, two turns out on the high-speed and 22 out on rebound.

 

Q: HOW DOES THE 250SXF HANDLE?

 

A: The hard truth is that the KTM doesn’t handle as well as some of its competition. Conversely, it handles much better than some of its competition. In plain language, it isn’t the best handling 250 four-stroke and it isn’t the worst. It’s workable. Coming from the MXA wrecking crew, that is a compliment. For years, KTM’s engineers have tuned in considerable understeer. For the life of us we don’t know what they were thinking. Thankfully, KTM’s American race team played a hand in developing the pre-pro KTM 250SXF, even sending in-house test rider Casey Lytle to Austria to work out some kinks. The international input resulted in a chassis that is much better at turn-in than any previous KTM. The understeer is lessened, and while the chassis is in no danger of suffering from oversteer, we think it is an acceptable platform to work from.

 

Q: HOW GOOD ARE KTM’S TIRE CHOICES?

           

A: American-bound KTM’s get Bridgestone tires. In an effort to avoid the negative comments they received when they spec’ed Bridgestone 401/402 and 601/602 tires on their bikes, KTM equipped the 2006 bikes with old-school M59 fronts and M70 rears. This is probably the best possible Bridgestone choice for intermediate-to-soft terrain. If you ride on hard or hard-to-intermediate terrain, you will find the tall knobs of the soft-terrain ?Stones very nervous.

 

Q: WHAT DID WE HATE?

 

A: The hate list:

(1) Front fender: If it didn’t have a fender brace, it would dribble off the front tire like a basketball. No other bike needs a fender brace.

(2) Top shock bolt: Watch the top shock bolt. It comes loose with regularity.

(3) Hot-start button: KTM’s hot-start button is mounted on the bars, but the plastic lever is exposed to danger on top of the clutch master cylinder

(4) Number plates: Would it kill KTM’s side panel designers to add an extra two inches of plastic to the bottom edge so that numbers would fit on the number plates? Just a thought.  

(5) Triple clamps: We want the fork offset set on 18mm. KTM sends it over on 20mm. You can switch it yourself, but you need a modicum of skill to do it.

(6) Rims: Black rims are cool to look at, but not after a couple months of racing. We don’t like the way they look after they get stone dings and tire iron marks on them.

 

Q: WHAT DID WE LIKE?

 

A: The like list:  

(1) Handlebars: Renthal FatBars. Nice. Although we prefer a slightly taller bar than stock.

(2) Swingarm: The 2006 KTM swingarm is one-piece. It is something that KTM tested when they owned Husaberg. Very trick.

(3) Gas cap: There is a learning curve with KTM’s new quarter-turn, aviation-style gas cap, but once you learn its peccadilloes, it is a thousand times better than KTM’s previous midget-sized hole.

(4) Tranny: You gotta love the six-speed tranny. The gear ratios are close enough to magnify the power at each shiftinstead of deaden it.

(5) Brakes: The front brake has always been very good, but the rear suffered by comparison. KTM put a lot of effort into fine tuning the feel of the rear brake. It must have worked, because the old complaints about squealing, fading and grabbing are nonexistent on MXA test rider reports.

 

Q: WHAT DO WE REALLY THINK?

 

A: Are you a rebel? Do you have the intestinal fortitude to buck the establishment? If you do, the KTM 250SXF is the bike for you. It stands out in a crowd. It is a terrific 250cc four-stroke motocross bike. o