French Flat-Twin

FRENCH FLAT-TWIN

ROUNDUP

DOES THE WORLD NEED A French motorcycle manufacturer? Voxan thinks so. And now, so does Midual.

At the moment, the Midual is complete fiction. Should all go well, it might become metal by mid-2003. The bike is the creation of Olivier and Francois Midy, with styling by Glynn Kerr. Its central feature, its claim to European character, is its longitudinally mounted, 875cc flat-Twin. One cylinder points forward, the other backward in the fashion of the pre-war Douglas machines.

Midi’s determination to repackage the valuable qualities of the opposed-Twin should be applauded. First, it makes both primary and secondary vibration completely self-canceling. As with BMW’s Boxers, there remains what is called a “rocking couple.” This is caused by the fact that the two cylinders cannot lie along the same axis, but can be only as close as two crankpins, spaced 180 degrees apart. A second advantage is what the Midual document calls “cyclic regularity.” A 180-degree flat-Twin fires every 360 degrees-even spacing of power impulses.

With no need for its liquidcooled cylinders to project into the airstream, the Midual orients its engine with cylinders in foreand-aft positions, canted forward 25 degrees to provide clearance for front wheel movement. The engine has four valves per cylinder, served by vertical intake and exhaust tracts that enter and leave the heads at right angles to the cylinder axes. The crankshaft drives a half-speed idler shaft above the crankcase via a belt, from which separate belts on right and left sides carry the drive to the heads.

Midual’s 94 x 63mm bore and stroke produce 875cc of displacement. Why not a full liter? One reason might be to avoid direct comparison with the already established lOOOcc Twins.

Marketing types allude to the engine’s output favoring torque over peak power. At 1.5:1, the bore/stroke ratio is modern, like that of highrpm sportbike engines. The stroke is usefully shorter than the 66mm favored by Ducati and its emulators. It would be very easy, cylinder-stud location permitting, to make a lOOOcc version at 100.4 x 63.0mm.

Wheelbase for the two foamand-resin prototypes exhibited at the Paris Show is 56.7 inches.

WP suspension includes an inverted fork and a direct-acting shock under the gas tank, operated by a long rod from the top triangle of the swingarm. Brakes are by Brembo.

About the M¡dual’s looks, stylist Kerr says that a cultural revolution occurred in the early ’80s, when “we finally accepted the fact that the engine and each mechanical component are an integral part of the style.” In other words, machine mechanicals are more than just something onto which to bolt style in the form of swoopy, colorful plastic panels. They are the style, defining the basic character of the machine. This means that there is no single, optimum, best-ever engine or chassis architecture now that engineers can make them all go, handle and stop.

Which means that configurations such as BMW’s Boxer, Moto Guzzi’s mulo meccanico and Triumph’s long-stroke Triple continue to exist and even thrive. For the same reasons, there may be room for Midual.

—Kevin Cameron