THE KTM 250SX is the revelation of the MX2 class here in Australia and in 2014 Brenden Harrison, Kale Makeham and Dean Porter will be looking to put the power of the mighty two-stroke to the ground in the hope of topping a field full of four strokes in the MX Nationals and Australian Supercross Championship.
Cycle Torque’s dirt bike guru Darren Smart took delivery of a brand spanking new 2014 KTM 250SX recently and over the next 12 months will give you a seat of the pants idea what it’s like to ride and race the same bike KTM is hinging its MX2 title hopes on. Over to you Smarty!
The first thing you need to know about the KTM 250SX two-stroke is that over the years it has benefited from every major change that KTM has made to its SX-F four stroke models: suspension, chassis, swingarm, wheels, brakes, triple clamps, seat, handlebars, plastics, airbox and airfilter.
You name it, the KTM 250SX has the latest and greatest technology from the Austrian marque.
So with that in mind it’s obvious the big difference between my new ride and the KTM 450SX-F I rode throughout 2013 is going to be the carburetted 50 horse power 250cc two-stroke motor instead of the fuel injected 57 horse power 450cc four-stroke power plant.
Hmm, this is going to be interesting.
The big kicker with the 250SX is that at 96.3kg it’s just over 10kg lighter than the 450SX-F (107kg) and 6.5kg lighter that the 250SX-F (102.8kg) so in theory it has the power to weight advantage over the four strokes.
That said, it definitely feels faster than the 450 thanks to the explosive power delivery but in reality a modern 450cc four-stroke motocross bike eats the 250cc two-stroke on the race track.
My first outing on the KTM 250SX was on the undulating natural terrain motocross track at Queensland Moto Park, a track that has plenty of hard acceleration and braking with everything from big sweeping turns to flat hair pins with plenty of braking bumps and acceleration ruts. Perfect.
I put all of the suspension clickers to the middle setting, set the race sag to 100mm and hit the track. After a couple of warm up laps I starting getting into a rhythm and managed to put together three good motos with absolutely zero changes to the suspension settings.
The first thing that comes to mind after my first day on the 250SX is how easy it is to change direction when diving from corner to corner.
Blasting through a fast right hand sweeper then braking hard for a tight, downhill left hand hair pin was an absolute breeze and I found myself pushing harder and harder into each corner with the front end extremely well planted when tipping in under brakes.
KTM really has the best brakes on the market and the suspension at both ends worked a treat on the day though I will be playing with the suspension when we starting hitting different tracks.
OK, the thing handles great, what about the power? Well, that was the part that took the most to get used to.
Around the very same track on the 450 I was able to pull the throttle on very early mid track and blast from corner to corner but on the 250SX the power is just too brutal to simply pull the throttle to the stopper without the back end wanting to light up and throw you into a big speedway slide so I found myself looking for something to bounce off to change direction while accelerating.
The changes to the 2014 motor has definitely given it a smoother bottom end and mid-range compared to the 2013 model but it still hits like a 120kg nite club bouncer when you get into the meat of the power band.
Having not ridden a modern two-stroke at pace for some years I was definitely running wide on most of the corner exits in the hunt for a berm or track edge to stop the back end from skipping out but I think more seat time should give me a little more confidence and throttle control.
The hydraulic clutch on all KTMs work a treat and the 250SX is no different. I was thankful for it as I kept a finger hovering over the clutch lever every time I was ripping out of a corner because the front end was looking to head for the sky when the rear end grabbed traction.
It really is a beast to ride but I was having an absolute ball blasting from corner to corner and trying to keep everything heading in the right direction without me landing on my head. Sensational!
So, what is new for 2014?
Ignition: The ignition mapping has been advanced to work in unison with the updated combustion chamber.
Chain Guide: The chain guide mounts on the swingarm have been stiffened while the chain guide itself is smaller, flexes more and is marginally lighter.
Clutch: The SX now gets the SX-F Damped Diaphragm Steel Belleville washer-activated clutch with a new reinforced inner hub.
Cylinder head: The combustion chamber has been updated with a new squish and shape. Note: the compression ratio remains the same as 2013.
Front Brake: The master cylinder has a new reservoir and a smaller piston diameter (down from 10mm to 9mm). There is also a new brake lever and brake pads.
Jetting: N1EH needle instead of the leaner N1EI needle.
Petrol Cap: The internal threads on the cap have been reworked for more positive engagement, and the gas cap has a new, low-profile shape.
Plastics: The radiator shrouds, air filter cover and winglet graphics above the shock bladder receive the in-mold treatment.
Reeds: KTM has dumped the Moto Tassinari reeds in favour of a Boyesen reed they designed themselves but they still used Boyesen’s all-new RC2 performance-weave carbon fibre petals and it now fits into the inlet of the engine cases at a steeper angle.
Seat foam: The foam core of the seat has been reformulated to be softer and more reliable.
So that’s a great start for 2014. Over the next nine months or so I will keep you posted on my time with the 250SX, there is some suspension and jetting changes that will be played with and even a couple of teeth smaller on the rear may help smooth the motor out a little.
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