FIRST LOOK! 2019 KTM 125SX, 150SX & 250SX TWO-STROKES

On Jul 3, 2018 Last updated Jul 3, 2018

2019 KTM 125SX.

2019 KTM TWO-STROKE FRAME
All 2019 KTM SX models feature lightweight chromoly steel frames in various profiles including hydro-formed elements produced by WP Performance Systems with state-of-the-art robots. They feature optimized stiffness (2% stiffer longitudinally and 10% stiffer torsionally). The head stays are aluminum for all models (new on the 250 SX two-stroke). New frame guards improve grip and the right one is heat protector for the muffler/silencer. The subframe is 900 grams (32 ounces) lighter and 40mm longer than before.

The 125/150SX engine rear can be switched back and forth between 125cc and 150cc displacement with just a cylinder, piston and head change.

2019 KTM 125/150SX ENGINE
The KTM 125/150SX engine is the most powerful engine of the class, but for 2019 it gets a reworked 54mm-bore cylinder with an improved power valve system, including a sophisticated mechanism for the lateral support exhaust ports. A new layout of the exhaust ports increases the engine performance. In addition, the upper contour of the exhaust port is now machined to guaranties more accurate port timing. The KTM 125SX engine design allows an increase of the displacement from 125cc to 144cc just by replacing the cylinder, piston and head without changing the crankshaft.

The new DS (diaphragm steel) clutch features a one-piece clutch basket combined with the primary gear. both milled in one piece from high-strength billet steel, the engine width at the clutch case is reduced by 10mm.

The 125/150SX is fitted with a newly designed exhaust pipe and silencer. The pipe is produced with the latest 3-D stamping technology for an optimized shape. In addition the molded plastic silencer bracket is replaced by a welded aluminum bracket to reduce weight.

A new airbox has been completely reworked for increased flow. This improves throttle response. The large Twin-Air air filter is mounted on a stiff cage, which minimizes incorrect installation of the filter and cage. The filter can be changed without tools in seconds.

The 125/150SX are fitted with a six-speed transmission made by F1 supplier Pankl. The 38mm flat-slide Mikuni carb gets new jetting specs to adapt to the new airbox and exhaust design.

Note the longer rear axles slots.

2019 BODYWORK & SEAT
The all new-plastics that provide perfect ergonomics and contact points for the rider, maximum freedom of movement and improved handling. In addition, the I-beam design for the front and rear fenders are prime examples of an intelligent design, which guarantees maximum stability at lowest weight through a well thought-out structure and mounting.

A newly shaped seat provides improved ergonomics and better seat comfort. Due to newly developed silicone strips the seat cover provides better feel and grip. The seat installs with one long bolt from the left side of the frame for easier removal and installation.

2019 SWINGARM
All 2019 KTM big bikes models are fitted with a reworked cast aluminum swingarm featuring a longer slot for the rear axle. This allows the adjustment of the rear wheel in a position up to 5 mm further back which gives the rider the option of gaining more straight line stability for fast tracks and whoops. The single-component casting process offers low weight and a perfect flex behavior.

2019 TWO-STROKE FUEL TANKS
The 125SX, 150SX and 250SX models are fitted with newly designed lightweight polyethylene tanks that improved ergonomics. Fuel capacity 1.85 gallons of fuel.

2019 COOLING SYSTEM
All 2019 KTM models feature newly designed radiators which are mounted 12mm lower than the predecessors. This lowers the center of gravity and in conjunction with a new radiator shape they match perfectly with the design of the new radiator shroud to make the bike narrower and easier to get forward on the bike. Thanks to calculated liquid circulation (CFD) and improved air ventilation cooling is improved. The coolant tube, that passes through the frame, is 4 mm larger to improve coolant flow from the cylinder head to the radiators more efficient.

2019 KTM WHEELS
The KTM wheels feature CNC machined hubs and high-end Excel rims, but for 2019 the aluminum nipples will feature a reworked design to reduce the frequency of spoke tightening. The tires are a Dunlop Geomax MX3S combo.

2019 KTM 250SX TWO-STROKE

2019 KTM 250SX ENGINE
The 2019 250SX engine features a cylinder with a twin-valve-controlled power valve system, counter balance shaft for low engine vibration, five-speed transmission and a hydraulically operated DDS clutch. With a 66.4mm bore, the power characteristics can be changed in seconds thanks to two supplied power valve springs and a preload tension adjuster for the main spring. The 250SX engine is raised by 1-degree around the swingarm pivot improving the handling and front wheel grip. Plus, the head stays brackets are now aluminum instead of steel to reduce vibration. The 250SX gets a reworked water pump casing to optimize flow for more efficient cooling.

The 250SX uses the KTM-developed damped diaphragm steel (DDS) clutch with a wear-free steel basket. This DDS design uses a diaphragm spring (Belleville washer)instead of the usual coil springs, which makes for easier clutch action. The diaphragm spring also leaves sufficient space for a rubber damping system integrated into the clutch hub, which benefits both traction and durability. The Brembo hydraulic clutch mechanism produces controlled modulation of the clutch.

The 2019 KTM 250SX has a newly designed exhaust pipe and silencer. The pipe is produced with the latest 3-D stamping technology for an optimized shape. In addition, the molded plastic silencer bracket is replaced by a welded aluminum bracket to reduce weight.

The 38mm flat slide Mikuni carburetor has new jetting specs for 2019 to work with the new airbox and exhaust design.

2019 KTM 250SX TWO-STROKE HIGHLIGHTS
Seat: newly shaped seat provides improved ergonomics and better seat comfort. Due to newly developed silicone strips the seat cover provides better feel and grip. The seat installs with one long bolt from the left side of the frame for easier removal and installation.

Swingram: The 2019 KTM 250SX cast aluminum swingarm features a 5mm longer axle slot to allow the rear wheel up to 5 mm further back.

Gas tank: The 250SX has a lightweight polyethylene tanks with improved ergonomics. Fuel capacity 1.85 gallons of fuel.

Radiators: The radiators are mounted 12mm lower than last year to lower the 250SX’s center of gravity. The new radiators and radiator shrouds make the bike narrower. Thanks to calculated liquid circulation (CFD) and improved air ventilation the cooling is improved. Additionally, the coolant tube, that passes through the frame, is 4 mm larger to improve coolant flow from the cylinder head to the radiators more efficient.

Wheels: The 250SX wheels feature CNC machined hubs and high-end Excel rims. Most importantly, the new aluminum nipples feature a reworked design to reduce the frequency of spoke tightening the spokes. The tires are a Dunlop Geomax MX3S combo.