Yamaha's Latest V-Four

Kenny Roberts rode a new Yamaha VFour in the Austrian Grand Prix. The machine’s engine hangs from the aluminum frame and the triangulated swing arm uses levers and pivots to operate a horizontal, single shock absorber mounted across the frame.

The new engine is smaller and lighter than the previous square Four, using two carburetors and two gear-driven rotary valves to feed the four cylinders from between the V. In addition to rotary intake valves, the engine has Yamaha’s barrelshaped exhaust Power Valves, which raise or lower the exhaust port height to produce maximum torque for a given rpm. Exhaust pipes from the rear cylinders

run straight back underneath the seat.

It’s interesting to note that the triple clamps on the forks are straight across with no offset. As shown in this photo, the bike has an 18-in. front wheel but 16-in. magnesium wheels have already been purchased from Morris.

The bike is very narrow and unofficial sources place its weight at less than 285 lb. Engine weight can be carried very low without reducing cornering clearance because the engine is very low. As a result the bike should be easier to flick from side-toside in ess-turns or chicanes.

Kenny's new bike. The CDI ignition is located on the left end of the rear crankshaft. The dry clutch is on the right side of the engine.

YAMAHA'S LATEST V-FOUR