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Test: Mototech-KTM RC4 690

The racetrack prototype

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The KTM 690 Duke R, converted by Mototech into a true racer, proves that less is often more. The kit bike passed its baptism of fire in Ledenon, surprising with top lap times, brilliant handling and rideability.

The gap in KTM’s single cylinder model range is obvious. Next to the 690 Enduro are the 690 Supermoto and 690 Duke. All motorcycles with wide tubular handlebars and an upright seating position. Where is it, the 690s with clip-ons, full fairing and RC8 optics? Is the design department overwhelmed, the marketing blind, or is the controller simply on the brakes??

Anyway, the days without a KTM 690 super mono racer are over now. Rudiger Kranz from Mototech in Denkendorf (www.mototech.de) transformed one from KTM 6th90 Duke R in a race bike baptized RC4. The fact that not only a technically but also optically convincing motorcycle was created has a lot to do with Rudi’s friend Josef Iker (www.imm-gmbh.com). The gifted mold maker, usually working in prototype construction for small fish like Porsche and Mercedes, gave the Mototech prototype its convincing appearance. He created the fairing package, integrated the standard rear light and headlights into the GfK-carbon mixed dress, built the carbon airbox, the twelve-liter fuel tank in the rear frame and the dummy tank. Kranz took care of the preparatory work. He invented clever details, such as the footrest retaining plates, which are identical on the left and right, constructed brackets and clamps, and thus ensured that not only every 690 Duke can be converted into an RC4, but can also be upgraded again. This is possible because Kranz only uses original holes in the frame or works with clamps. Plug and play, so to speak. So the complete conversion kit remains affordable and only comes to 4800 euros (TÜV report in preparation).

Technically, Kranz had to change relatively little on the 690 Duke in order to convert it into the RC4. To trim the chassis geometry in the direction of a super sports car (66.0 degrees steering head angle), all he had to do was lengthen the strut. In addition, the suspension specialist naturally adapted the shim equipment in the fork and shock absorber for racetrack use and breathed the finest responsiveness into the dampers. The complete drive train including the exhaust and the secondary transmission remained as standard: only the intake tract was changed. Thanks to the full fairing and the new airbox, the 690 single is now forced ventilation via the Ram Air system.

A little surprise when you look at the scales: Despite the full fairing and full twelve-liter tank, the RC4 is a whole 7.5 kilograms lighter than the standard Duke R. Okay, mirrors, pillion pegs and license plate holders are missing, but the rear light, the heavy one Headlights and the complete wiring harness are also on board. Well done so far. But how does the baby drive now? The winding mountain and valley railway "Ledenon circuit" in the south of France is the perfect area for the Mototech-RC4. Blind corners, huge differences in altitude and relatively short straights offer everything the racing dwarf, which has just 70 hp, needs to compete against the 1000-cc, which is sometimes more than 100 hp. 

Jahn

The footrest carriers are interchangeable on the left and right.

At the end of the start-finish straight, it goes over a small hilltop that obscures the view of the “Triple Gauche ”behind it, a triple left that becomes tighter and tighter towards the exit of the curve. On a 1000 meter, maximum adrenaline rush is the order of the day and a lot of courage is required if it is to cross the hilltop unchecked. On the RC4 you sail over it completely relaxed, the single is fully onions in the sixth gear, which is a little too long. Bang, then a sudden straightening of the upper body! Get out of the great wind protection of the tightly cut, but very well protective fairing. This action alone creates so much air resistance that you can downshift to fifth and turn into triple gauche without braking – at least in theory. Anyone who really turns without braking has a lion’s heart. The author’s weaker self struggled every lap, but still couldn’t keep his fingers off the brake lever.

Nevertheless, the entry speed of the RC4 is fantastic, the competitors of the race training organized by BoSee (www.bosee-team.de) can be nibbled either inside or outside. Which is more due to the RC4 than to the other participants. Because the disguised KTM allows an incredibly wide choice of lines despite the high cornering speed. If it has to go around the corner, it literally sticks to the curbs, if it can be far, it can be directed to the millimeter with minimal steering impulse. And without any effort. So in the long links you can dance around your fellow competitors in a slalom. The tailor-made ergonomics also contribute to this lively character. The perfect position of the handlebars, rests and seat pads creates a compact and relaxed sitting position from which the 151.5 kilo lightweight racing gnome can be moved effortlessly.

Jahn

Where other lines erase, the RC4 accelerates mercilessly.

In addition to the steering behavior and neutrality in bends, the response behavior and the operation of the damping elements are also top class. The fork and shock absorber sensitively smooth out small wrinkles in the asphalt and cannot be disturbed by edges or holes when braking or accelerating. They always have reserves, and thick. The most fascinating thing about the RC4 is not its playful, nimble handling. No, for a pilot coming from a 600 or 1000 series, it’s the braking, turning and acceleration points. On the RC4 you brake as late as never before, steer more precisely than usual and accelerate earlier and harder than usual. By the way, it is remarkable how smoothly the single accelerates in a deep lean angle.

Of course you are slower than usual on the straights with the 70 hp of the 690, but that is easy to cope with given the good lap times of 1.35 minutes. If you would like more power, you can order an 80 hp kit for the single from KTM. PS will persuade Mr. Kranz to get the kit and then bring the RC4 out for a race – let’s see …

Supermoto

Test: KTM 690 Duke R

The new KTM 690 Duke R

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Technical specifications

Jahn

The original air filter resides in the carbon airbox under the dummy tank.

Mototech: KTM RC4 690
drive 
Single-cylinder engine, four valves / cylinder, 51.5 W (70 PS) at 7500 / min *, 70 Nm at 5500 / min *, 690 cm³, bore / stroke: 102.0 / 84.5 mm, compression ratio: 12, 5: 1 , ignition / injection system, 46 mm throttle valves, hydraulically operated multi-disc oil bath anti-hopping clutch, G-Kat, chain
landing gear 
Steel tubular space frame, steering head angle: 66.0 degrees, caster: k. A., wheelbase: 1450 mm, upside-down fork, Ø fork inner tube: 48 mm
Wheels and brakes 
Light alloy cast wheels, 3.50 x 17 "/ 5.00 x 17", front tires: 120/70 R 17, rear: 165/55 R 17, 320 mm single disc brakes with four-piston fixed callipers
Weight (full tank) 151.5 kg
Kit price: 4800 euros

tires
Dunlop KR 106/108 Since the Mototech-RC4 stands at 3.50 "and 5.00", PS used the extremely adhesive Dunlop slicks in 250 dimensions for this test. On the front wheel we put the KR 106 in 120/70 R 17 in mixture “6743”, at the rear the KR 108 in 165/55 R 17 in mixture “3854”. Neither the ups and downs of the Ledenon course nor the 151 kilograms of the 70 hp Mototech or the 35 degrees air temperature could bring the skins off track. They put up with the toughest acceleration maneuvers and ultra-late braking attacks like nothing, and their wear pattern looked tip-top thanks to the perfect chassis. The reward for this work were permanent lap times in the high 1.35 min range. And that without wobbling, sliding or anything.

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