Reincarnation of a classic
Ken and Barry Horner, were both keen sidecar racers in the late 1960s and early 1970s; Barry going on to top-level success in the era when beating Geoff Taylor and Barry Frazer was headline stuff. In 1981, he came within one lap of winning the Australian Sidecar Grand Prix at Mount Panorama, Bathurst. After recovering from a bad start, Barry powered past multi-champion Geoff Taylor and had the race in the bag until he broke a chain.
Thereafter, both drifted away from the sport to concentrate on building a thriving engineering business in Melbourne, specialising in air-powered starter motors for use in hazardous situations. Their modern factory has accumulated vast amounts of sophisticated CAD-CAM machinery and this set the Horner boys thinking that it was now within their means to re-create the iconic machine of their youth – the 1000cc Vincent originally designed by Australian Phil Irving. With the blessing of Phil’s widow, Edith, Ken and Barry began the Irving Vincent project – a plan to bring the 60-year old design into the 21st century.
“We weren’t interested in just producing parts to keep Vincents running – other people have been doing that for years” explains Ken. “We wanted to make complete bikes with the engines based on the original design, but re-engineered to correct the shortcomings.” In recent years, the Horners have been heavily involved with engine development for Garry Rogers Motorsport, one the most successful teams in Australian V8 Supercar racing. “These V8s are just two-valve pushrod engines, so we reckoned that we could apply the same principles to the Vincent design. We treat this as a V8 with six cylinders taken off it.
One of the biggest bugbears in extracting extra power from a Vincent has always been the lubrication system, which Ken described as ‘quite horrific’. Any attempt to improve camshaft performance generally requires increasing valve spring pressure, and the standard oil pump and internal oiling system simply cannot cope with the extra duties. The camshaft, followers and valve gear are usually the first to suffer, especially in that nervous period when the engine is fired up and the oil begins to trickle through. Horner’s solution was to replace the standard pump with a two-stage unit, forming both pressure and scavenging functions, in the space at the front of the engine where the magneto usually sits. At the end of the pump is a 24-slot ignition trigger linked to a Motec ECU which has been specially adapted to suit the 50 degree V.
The first complete Irving Vincent was a 92mm-bore 1300cc Mk 1, which uses a TIG welded box section top chassis fabricated from 16-guage chrome-moly steel that doubles as the oil tank, with tubular chrome-moly of the same gauge comprising other parts of the frame and swinging arm. The steering head is fully adjustable by means of eccentric sleeves. Modified Norton front forks are used with Fontana hubs for the 18-inch spoked wheels, although the Horners have also produced their own hubs and drum brakes, machined from solid. Rear shock is an Ohlins. Finished in gleaming black, the Mk1 clearly has a foot in the earlier camp – a styling exercise reminiscent of the Egli Vincents of the 1970s.
On the other hand, the 1600cc Mk 2, also known as the Mega, is pure superbike. Finished in striking metallic blue, red and white with the stars of the Australian flag, the Mega uses wheels and forks and brakes sourced from a 996 Ducati, along with a much beefier swinging arm than used on the 1300. The engine has shown no less than 166 bhp at 6,000 rpm, with a stump-pulling 158 foot/pounds of torque. The immense bottom-end figures may be in part due to the relatively small (48mm) inlet tract on the prototype 1600, and this may be opened out in future. Injector bodies are the same as on the racing Holden V8 engines, with a fully-computerised Motec ECU taking care of engine management. The 1600 was demonstrated at the island Classic at Phillip Island in February in front of a large an appreciative audience.
As a further showcase for their new products, Ken and Barry have constructed an outfit for the historic Forgotten Era class, which caters for motorcycles as raced in the period 1973 to 1980. Powered by a carburettor version of the long stroke 1300 Mk1 engine, the creation bristles with original thinking and superb craftsmanship. The engine breathes through twin 45mm Gardiner flat-slide carburettors fed by SU-type bowls, with fuel delivered from the sidecar-mounted tank via an electric pump. Final drive is achieved by chain from the right side countershaft to an idler shaft running transverse and which forms the pivot for the rear suspension. The final rear chain drive exits on the left side to the rear wheel. Up front, a twin-shock system of the Horner’s own design (using Ohlins shocks) is controlled by a rocking coupling – the theory being to give the fat Avon slick the maximum contact patch with the road and thereby reduce the understeer on the right handers that habitually challenge outfit design.
In the near future, the Horners hope to produce Irving Vincents for sale, and there is no shortage of potential customers around the world.