Improvements and new tech hallmark the 2015 KTM models for the Orange Brigade.
KTM has released technical information on its complete lineup of 2015 KTM motocross models. The motocross range once again includes a diverse range of engines, of both the two- and four-stroke variety, and the 2015 models incorporate a host of changes, including a new chassis and new suspension.
Chassis/Swingarm
KTM steadfastly refuses to join the aluminum perimeter frame club, and we couldn’t be happier about that because, if for no other reason, variety is the spice of life. Frankly, none of KTM’s extensive R&D has proved that an aluminum chassis performs any better than its chromoly steel designs.
For 2015, the chassis, which is manufactured by KTM subsidiary WP Performance Systems, features chromoly steel sections united by a new cross tube that features machined (not welded) connectors for the linkage rods to the frame. The machined design is said to provide more exact production tolerances and give more consistent chassis characteristics than the welded design. It also shaves 58 grams of weight from the chassis.
The chassis is mated to a new cast-aluminum swingarm that KTM says was designed using the latest in calculation and simulation software. The wall thickness has been refined for minimum weight while providing optimum stiffness. KTM paid close attention to the flex characteristics of the swingarm to ensure excellent traction, stability and rider comfort.
Suspension
The 2015 SX models also receive new, fully adjustable rear monoshock by long-time KTM in-house supplier WP Suspension. The shock has been been re-valved and set-up to work with the new linkage geometry. The shock stroke is 4mm longer than before but allows the same amount of wheel travel because of a new linkage design with revised geometry developed in testing with the Red Bull KTM Factory Team along with KTM’s US R&D department.
The linkage revisions are claimed to provide an optimized rising rate that utilizes a higher starting rate to achieve a flatter, less progressive curve for better control. A new production process for the triangle and pull-rod saves 40 grams of weight.
Up front, the US-bound SX models will wear a WP 4CS fork. This is a completely new four chamber fork that KTM says has been specifically designed and tested for motocross. The advanced 4CS fork is supposed to offer improved damping, is lighter than previous models and can be adjusted easily for compression and rebound via the dials on the top of the fork tubes.
New and Revised…
For 2015, the front axle has been reduced in size from 26mm to 22mm to reduce weight and offer a better front-end feel. The smaller axle also made it possible to move it back 2mm in the axle clamp. The adjusted offset and increased trail is claimed to provide more stability.
The fork protectors have been revised for 2015, primarily to fit to the new axle clamps but also to save weight. They also allow easier access to the fork legs for quicker cleaning and faster maintenance.
CNC-machined triple trees have been a KTM trademark for years. For 2015, KTM slightly revised them by altering the O-ring support for the lower bearing on the steering stem. It is now made of aluminum to save 22 grams of weight, and the steering stem bolt is also 8 grams lighter.
The main focus of the KTM’s bodywork was to achieve complete harmony between rider and bike, right down to the finest details. KTM says that the front fender is a prime example of a molded polymer component, gaining maximum stability through a well thought-out structure and mounting system. For 2015, the bodywork will be decorated with updated graphics.
The 2015 SX models also receive new Excel rims colored black for aggressive looks. The rims are mated to lightweight CNC-machined hubs via Excel spokes with lightweight aluminium nipples, and they are wrapped in Dunlop’s excellent Geomax MX52 tires. The rear wheel is also fitted with a new sprocket design that is 50 grams lighter than the old design.
All SX models are fitted with the super-strong, tapered Renthal Fatbar 827 handlebar clamped in a mount that offers adjustment to four different positions. New, softer two-compound grips are also found on the 2015 models.
Four-Strokes
KTM 250 SX-F
The 250 SX-F was once again a 2013 World Championship Motocross winner in MX2 and also won an AMA Supercross Lites Championship in the hands of Rockstar Energy rider Jason Anderson in 2014.
Revisions to the 2015 250SX-F include a lighter clutch basket and new clutch springs for a more consistent behavior and long-term durability. The CSS (coil spring steel) one-piece clutch system. The clutch continues to use the Brembo hydraulic system for light operation and controllable modulation. Its fuel-injected, DOHC, four-valve single also gets new O-rings on the oil pump suction screen for increased durability. Some of the technical highlights of the 2015 KTM 250 SX-F include:
– Compact DOHC engine with two overhead camshafts & DLC coated followers
– Titanium valves (intake 32.5mm, exhaust 26.5mm)
– A 14,000 rpm rev ceiling
– Flow optimized ports
– A forged box-type piston for a low oscillating mass
– A crankshaft that employs a plain big end bearing for longer service intervals
– New O-rings on the oil pump suction screen for increased durability
– A multifunctional counter balance shaft, which drives the water pump and timing chain for reduced vibrations
– An electric starter as standard, a clear advantage in the heat of the battle
– A lightweight and compact CSS clutch (coil spring steel) with eight clutch plates and a wear free steel basket
– New clutch basket with a weight-saving design
– New clutch springs for more consistent behavior under stress and over time
– A lightweight five-speed gearbox for precise & easy shifting adapted for the 250 SX-F
– An engine management system that offers the user the ability to change performance characteristics or read engine data with the accessory User-Setting-Tool
KTM 350 SX-F
The 350 SX-F won another MX1 World Championship in convincing fashion, and also dominated the Motocross of Nations in the hands of Italian moto superstar Antonio Cairoli. The 350 SX-F has become popular due to its combination of light weight, agility and a compact DOHC engine that offers open-class power in smaller-displacement, high-revving package.
Part of that high-revving character is due to lightweight titanium valves and DLC coated followers that reduce drag for brisk power delivery. Like the 250, the 350 also gets the new O-rings that increase durability on the oil pump suction screen, and the new, lighter clutch basket with new clutch springs to complement the CSS clutch. Technical highlights of the 2015 350 SX-F include:
– A DOHC Cylinder head with ultra lightweight titanium valves and DLC coated followers for easier power production.
– A crankshaft that employs a plain big end bearing and force-fitted bearing shells for longer service intervals
– New O-rings on the oil pump suction screen for increased durability
– A multifunctional counter balance shaft, which drives the water pump and timing chain for better simplicity and reduced vibration
– An electric starter as standard
– A CSS clutch (Coil Spring Steel) with eight clutch plates and a new steel basket that saves weight over the previous design.
– A lightweight five-speed gearbox for precise, easy shifting, adapted for the 350 SX-F
– An engine management system that offers the user the ability to change performance characteristics or read engine data with the accessory User-Setting-Tool
KTM 450 SX-F
The KTM 450 SX-F is the weapon of choice for the Red Bull KTM factory race team in the premier class of the Lucas Oil AMA Pro Motocross Championship, and thus far in 2014 has been undefeated through the first two rounds, thanks to the performances of Ryan Dungey and Ken Roczen. The 450 SX-F uses a different valve train design than the 250 or 350, with a compact SOHC engine that is tuned to deliver explosive but controllable power. Technical highlights of the 2015 KTM 450 SX-f include:
– A compact 60hp engine with a single overhead camshaft and the latest electronic fuel injection, which offers class-leading performance
– The single overhead camshaft controls four ultra-lightweight titanium valves via extremely rigid rocker arms, which are DLC coated on the intake side
– A rev ceiling of 11,500 rpm
– A three-layer head gasket for durability under the most extreme conditions
– Bore of 95.0mm with a lightweight box-in-box type piston for low engine vibrations
– A crankshaft that employs a plain big end bearing and force-fitted bearing shells for longer service intervals
– A side mounted counter balance shaft that also drives the water pump
– Electric starter as standard
– A DDS clutch with Brembo hydraulic system
– A lightweight five-speed gearbox for effortless shifting
– New O-rings on the oil pump suction screen for increased durability
– Engine management system for a spontaneous throttle response & possibility to change characteristics or read engine data with the available to purchase User-Setting-Tool
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