First Impression: 2017 KTM 250 SX

KTM basically took what they learned from the 2016 KTM SX-F’s and incorporated most of the chassis and suspension changes to the SX line. So what’s new on the 2017 KTM 250 SX? It would be easier to write you what ISN’T new on the 250 SX. KTM’s development target for the 2017 250 SX was to get weight reduction, centralize mass, improve the handling, get more power out of the engine, update the ergonomics, and give the SX an overall new look. Here is the breakdown of what’s new in, on, and around the orange machine:

The frame is lighter by 380 grams with 20% higher torsional rigidity and 30% less longitude stiffness, a steeper (0.4mm) steering head angle (10mm shorter overall wheelbase), a new smaller more compact subframe design made with new aluminum profiles which is 200 grams lighter, a WP AER 48 air fork (3.6 pounds lighter than the 4CS), an all new engine with a new die-cast crank design, engine covers, an additional counter balancer shaft, cylinder and cylinder head, a new weight optimized crankshaft, Mikuni TX 38 carb (previously a Keihin on the 2016 model), an updated pipe and silencer to match the new engine design and character, newly designed airbox and air filter, overall seat height is lower (20mm in the rear and 10mm in the middle), handlebar bend (height) is also 10mm lower, newly designed “No Dirt” foot peg design to keep mud/debris from getting your footpegs hung in the upward position, the swingarm’s internal structure is revised to match the flex character of the frame, 10mm longer rear brake pedal, less aggressive rear brake pads, a revised 22mm offset triple clamp, a throttle assembly that is made easier to adjust by the throttle housing itself, and finally lock on ODI grips find their way on the SX.

With it only being a few days after the Lucas Oil Pro MX National at Glen Helen we knew this would be a great test for the 2017 KTM 250 SX. Right after we kicked the KTM to life we immediately noticed that almost zero vibration was felt through the Neken handlebar. Compared to last year’s model that would shake your teeth out from your head, this is a very welcomed change. Acceleration out of corners is smooth and calculated and there is no violent two-stroke like hit to the KTM 250 SX. We actually liked this compared to the light switch delivery (or hit) of some two-strokes we have ridden lately, especially when Glen Helen’s bumps got bigger over the course of the day. The new KTM engine can and will oblige if you are a four-stroke type of rider and like to short shift. Shifting a little early on the SX is ok and pulled just fine up the steep hills of San Bernardino. The only thing you will have to remember is to down shift to second gear through most corners, as third gear is just too tall to carry (if you’re a two-stroke regular then you already know this). Top end is plentiful on the KTM and the new engine character pulls hard on top end just like it always has. The only part of the engine that may not have been as good as the 2016 model is over-rev. Last year’s model revved out further and the 2017 model may just be a tick off from that. We didn’t have a 2016 to compare back to back with, but this was something that was noticeable to more than just one test rider. Jetting on the orange smoker was crisp and clean, but we did end up going to a richer 450 main jet (up from a 440), to combat a little bit of detonation when revving out the KTM up hills. After changing the main jet out, the top end increased and over-rev was slightly better up steep hills and long straights. The new engine character is more four-stroke-esq than ever before. Lugging ability is still not like a four-stroke, but the overall rideability of the new 250 SX is better than it ever has been.


One thing we do know as of today is the 48mm WP AER fork is leaps and bounds better than the WP 4CS fork. Yes, you heard that right an air fork is better than a spring fork. Not that the 4CS fork was setting the bar that high for spring forks, but one thing is for certain the new AER fork has more comfort than its spring’d predecessor. The WP AER fork actually moves in the stroke unlike most every other air fork we have tried to date. We started out with a base air setting of 149 psi and by the end of our test day we ended up increasing the pressure to 151 psi, which helped some. With 151 psi now in the fork the AER fork had better hold up (damping feeling) coming down hills and hitting the steep jump faces Glen Helen provided. The front end didn’t dive as much and held up in the stroke much better for aggressive riding. What was impressive is that when we did increase the air pressure the fork didn’t get any harsher through the stroke. It feels like when we increased the air pressure it only affected the first half of the stroke and the second half felt that same. Increasing compression (stiffer) a couple clicks on the fork makes a noticeable difference through the whole stroke. When coming into corners with sizeable braking bumps the fork felt comfortable and didn’t give a harsh feel through the bars. Deflection was a non-issue and overall balance of the KTM was acceptable by all three of our testers. If there was one thing we could complain about was that we do wish we could get better damping feel on slap down landings.

We felt the rear of the KTM had a softer feel to it, but not on the shock’s damping side. We felt the shock moved in the stroke and had good damping feeling, but the overall energy absorption from the rear end was far better than we remember it being from any KTM two-stroke. Example: When hitting a square edge at high speed while sliding, the whole bike stayed planted and didn’t have a harsh feel or want to kick out on you. This feeling is very noticeable at Glen Helen due to the high speeds and tons of choppy square edge around corners.

Chassis feeling through corners felt good, not great, but just average. We did get some front-end push on tighter corners, but we will dissect this more in the coming days at more tracks. Stability was impressive and when we did get out of shape (cross rutting up hills) the bike always tried hard to get corrected and straighten up.

Is this the best two-stroke KTM has made? Even though we have only one day on it, it is hard pressed not to say “yes”, but for right now we will save judgment until we ride it on more tracks. Stay tuned to dirtrider.com for a complete evaluation, more updates and look for a test on this machine in an upcoming issue of Dirt Rider Magazine.

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