Filling the Gp Grids

FILLING THE GP GRIDS

IN A MOVE UNPRECEDENTED

in modern grand prix

motorcycle racing,

Yamaha has agreed to sell examples of the engine that powered Wayne Rainey to his 1990 and 1991 world championships.

Having a Yamaha GP race engine is all well and good, but you need a chassis to go with it, and that’s where ROC Competition enters the picture. ROC, of France, is offering for sale a machine it calls the ROC-Yamaha GP1. This is a fully fledged 500cc grand prix racebike, powered by an engine very similar to that which propels Rainey’s bike.

How similar? ROC says, “We ask that members of the media refrain from pressing our customers to reveal details about the engines. As a prerequisite to purchase, all customers have signed an agreement to keep technical details secret, so please refer all technical questions concerning the engines to Yamaha directly.”

What is known about the engine is that it remains a twin-crank design, with bore and stroke of 56.0 x 50.6mm, which works out to 498cc. It uses single-ring pistons, roller and needle bearings throughout, seven transfer and three exhaust ports per cylinder, electronically controlled exhaust power valves, flat-slide Mikuni carbs and electronic ignition with programmable advance curve.

The chassis is the usual box-section aluminum twin-spar design, with special inserts in the steering head to provide head-angle adjustments. It uses a triangulated box-section aluminum swingarm mounted on needle roller bearings, and rolls on Marchesini cast magnesium wheels.

The fork is an Öhlins upside-down unit, and the shock also is by Öhlins-an interesting detail, as Yamaha owns a stake in the Swedish suspension company.

Front calipers are by Brembo, and so are the 12.6-inch front rotors and the 8.7-inch rear rotor, while the rear caliper is by Nissin.

ROC says the complete machine tips the scales at 282 pounds, actually four pounds under the 500 GP minimum.

Cost for the bike is £75,000, or about $129,000.

Jon F. Thompson