Even Readier to Race
New track bike has more power, updated KTM RC8C suspension and aero nicked off the GP bike…
The second generation of KTM’S track-only RC8C gets a multitude of changes aimed at making it even more of an apex scythe. Power from the 889cc parallel twin is up by 7bhp to 135bhp at 11,000rpm, electronics are tweaked, suspension settings modified and the new wings are direct copies of the ones on KTM’S RC16 Motogp machine. It’s a tantalising blend of light weight – 142kg dry – and usable power.
Despite all the changes, the chassis and basic design remains the same, which is a tribute to the RC8C’S template: Kramer’s GP2-R. The German company specialises in using middleweight KTM motors to power wonderfully light, precise track bikes, and KTM did a deal in 2021 to rebadge the GP2-R as the RC8C. Consequently the new RC8C has some features unseen in other KTMS. The fuel tank is made of uber-tough rotomoulded plastic and sits under the saddle where it doubles as the rear subframe, and the space where the fuel tank would normally be is filled with a vast airbox. Also, as with the old RC8C, Kramer will handbuild the new bikes in their German factory. The power increase is the product of multiple tweaks. Valves are titanium, valve timing is changed, inlet and exhaust ports are machined for greater efficiency, the compression ratio is increased, there’s a new titanium Akrapovic exhaust, and throttle bodies are 48mm – up from 46. As before WP provide the suspension, but this time it’s the latest Apex Pro 7643 43mm forks and 7746 shock – the lightest race kit WP make. The base settings are slightly softer for better performance on bumpy tracks and with severe hangovers. As before you can adjust the steering head angle and swingarm pivot point to ruin everything.
The electronics are an evolution of the road-going KTM 890 Duke R’s, with two throttle response maps – PW1 for dry conditions and fit tyres, and PW2 for rain or when you’ve trashed your rubber. There’s also a new 10-stage rear slide adjustment and two levels of engine brake control.
Only 200 RC8C will be produced, each costing £34,999.
‘Settings softer for bumpy tracks and hangovers’
The new Horex VR6 Raw99 has an innovative carbon fibre steering head that saves 5kg over the standard model and adds torsional stiffness, plus carbon footrest hangers, mudguards, chain cover, instrument binnacle and headlight surround. That lot brings the overall weight down to just 216kg, but that’s surely not the main reason you’ll pay £43,000 for one of the 99 German curiosities to be built. No, the real selling point is that engine.
It first appeared in 2013 but it’s still like nothing else in motorcycling – the 1218cc motor is as narrow as most big inline fours, yet with six cylinders, a 9000rpm redline, a 161bhp top-end and three camshafts operating 18 valves. The Horex is motorcycling’s only TOHC.
The reason for a third camshaft is the cunning cylinder layout. With a standard V6 you need two camshafts for each bank of three cylinders, but the
‘As narrow as big inline fours, yet with six cylinders’
Horex V is so narrow – just 15-degrees – that the intake camshaft can be shared by all six cylinders. To get that narrow V the two banks of three are all in one block, with cylinders staggered and overlapped – it’s like two inline triples nestled as closely together as possible, then angled slightly so the con-rods all connect to one crankshaft. Because the top of the cylinder is flat the pistons are asymmetric, with a 15-degree slope on the top to create a conventional-shaped combustion chamber. It’s all distinctly odd, but the result is an engine that’s very nearly as smooth as a straight six (which has perfect balance), but far narrower. BMW’S fabulous 160bhp K1600 motor, for example, is remarkably narrow for six, but still 12cm wider than the Horex. And because the VR6 only uses one block and cylinder head, it’s cheaper and simpler than a standard V. The term VR6, incidentally, was coined by VW who produced a similar layout engine to power hot Golfs – the R stands for row, to indicate that it’s a cross between a V6 and an inline one.
So why doesn’t every manufacturer have a VR6 in their range? Well, it is way more expensive to make than an inline four, and Horex have patented its use in motorcycles.