The RC8R's upgraded four-valve cylinder heads have a more compact combustion chamber and altered porting for better flow, yet employ the same 42mm titanium inlet/34mm steel exhaust valves as the smaller-bore engine, each still carrying just a single spring. All-new camshafts with altered profiles delivering greater duration but unchanged lift also boast adjustable cam sprockets, which allows valve timing to be changed, useful in optimizing performance for Superstock racing, or any Superbike class like the German IDM series that require retaining some of the stock engine internals.
Nestled between the cylinders...
Nestled between the cylinders of the 75-degree V-twin engine, both the RC8R's water pump impeller and housing have been redesigned for improved flow to work with the larger radiator and shed the more powerful engine's increased heat.
All this lifts the claimed power of the RC8R to 170 horsepower at 10,250 rpm, a 15-horsepower hike over the RC8 but 250 rpm higher. Torque is also up to 90.7 ft/lb at 8,000 rpm (versus the older bike's 88.5 ft/lb at the same rpm). The extra heat generated is shed via a side-mounted oil heat exchanger, and larger coolant radiator with a redesigned water pump to increase flow.
Because we didn't ride the RC8R on the street, I can't say if the extra power has made a difference as far as its worthiness as a streetbike. But I'd guess it has, mostly because of the linear way in how the RC8R delivers its extra horsepower all the way through the powerband. Just as on the RC8, it starts pulling well from as low as 4000 revs, heading hard and strong for the 10,700-rpm rev-limiter with no steps in the power delivery. On the RC8, this smooth power delivery made the KTM seem not as exciting as its Italian rivals, but the RC8R's more aggressive character has certainly addressed that. Thanks no doubt to the one-point higher compression ratio and small 52mm throttle bodies held over from the RC8, as well as the new cam profiles, there's a real sense of the bike lunging forward out of turns. This is a thrilling bike to ride hard.
 Even though the bore is 2mm...  Even though the bore is 2mm larger, the RC8R's cylinder head features a smaller combustion chamber that works with the forged Mahle piston to boost compression ratio from 12.5:1 to 13.5:1, a significant increase. Valve sizes for the titanium intake and stainless steel exhaust remain the same; new camshafts sport adjustable sprockets. |  Brembo monoblock radial-mount...  Brembo monoblock radial-mount calipers grip 320mm discs on the RC8R's front brake system, providing supreme stopping power. Forged aluminum Marchesini wheels are lighter than the RC8's items for less unsprung weight, as are the Pirelli Diablo Supercorsa tires. WP fork features titanium aluminum nitride coating for less stiction. |  Like the RC8, the RC8R's valve...  Like the RC8, the RC8R's valve train uses finger followers to actuate the valves. This allows high rpm potential, although it also adds reciprocating valve train weight as well as bulk to the cylinder head casting. |
Ironically the RC8R is actually more controllable despite that extra power than its standard sibling. For instance, I've never had a problem with the RC8's gearbox, but KTM's transmissions upgrades (a reshaped gearshift arrester star introduced last September as a no-charge update) have improved its action considerably. Without a side-by-side comparison, it's impossible to tell how this performance stacks up against its Ducati rival, but from a seat-of-the-pants feeling I'd say the new KTM might now have the edge on bottom end and midrange acceleration--and it especially isn't as wheelie-prone as the Italian bike--but isn't quite as fast on top end. The revised twin counterbalancers (to take account of the RC8R's bigger pistons and different rods) seem to do an even better job of ironing out vibration from the 75-degree V-twin motor. The few extra tingles noticeable through the footrests once you revved the smaller-engined RC8 above 8000 rpm have now gone, another factor in making this bike less tiring to ride hard on.
 The 42mm titanium intake and...  The 42mm titanium intake and 34mm stainless steel exhaust valves (identical to the RC8 units) still utilize single valve springs to cut down on frictional losses and valve train weight. |  The KTM's transmission received...  The KTM's transmission received some subtle modifications, including the same reshaped gearshift arrester star that was an post-release update on the RC8, and revised engagement dog shape for the gearshaft pinions to avoid premature meshing. There is no slipper clutch in the RC8R gearbox, with an ECU-activated throttle bypass providing back-torque limitation instead. |  In order to transfer the additional...  In order to transfer the additional heat generated by the more powerful engine, a liquid-cooled oil cooler was added to the RC8R engine. |
Although the Keihin single-injector ECU is ideally mapped, with none of the abrupt pickup off a closed throttle that the RC8 sometimes displayed, KTM has provided two different throttle grip tubes with the bike, each with a different profile (no ride-by-wire yet, but KTM admits to working on it for the future). The "Race" version that comes standard has the usual circular arrangement, which delivers instant response without lacking control. The "Road" version has an eccentric cable pull that gives around 10 percent slower response until about half-throttle where it reverts to normal. It works, too; even though I didn't have any wet roads to ride on, I can imagine how this would be beneficial on slippery surfaces, or just for everyday street riding, because it makes the throttle pick-up quite a bit smoother and less aggressive.
The new KTM is a very reassuring bike because you feel in control even when riding close to the edge. The front tire feels planted on the tarmac, helped no doubt by that 54/46 forward weight bias that is quite atypical by V-twin standards. This gives you the confidence to use those fabulous Brembo radial-mount monobloc brakes (featuring 0.5mm thicker discs to help alleviate heat concerns with the RC8R's more aggressive racetrack intentions) to dive deep into turns and trailbrake toward the apex without any sign of instability. That's where the lack of a slipper clutch is cleverly masked by the RC8R's Keihin ECU mapping. By slightly opening one throttle butterfly valve on the rear cylinder, the system bleeds off engine vacuum to overcome the effects of engine braking while retaining most of the benefits.