Honda Nsr500
HONDA NSR500
Inside the Works Bikes:
THOUGH ALL FOUR OF THE MACHINES CONSIDERED major contenders in 500 GP racing are described as having V-Four, reed-valve, two-stroke engines, they have more differences than that simplistic description implies. For one thing, the Honda NSR500 has the only engine that uses a single crankshaft. But this engine could be thought of simply as an inline-Four with two of its cylinders rotated 112 degrees out of plane. Cylinders Two and Four point downward about 70 degrees below horizontal; cylinders One and Three lean forward about 50 degrees from vertical. But the crank throws are staggered accordingly (and each cylinder has its own separate crank chamber), resulting in the same even, 1 80-degree firing intervals asan inline-Four.
This a1~angement allows the Honda "V-Four" to be far narrower than a conventional inline-Four two-stroke. By rotating alternate cylinders out of plane, transfer-port width and cylinder diameter no longer dictate cylinder spacing; thus, the NSR engine measures less than 12 inches across its cases. The difficult problem of finding room for carburetors with this engine configuration was solved with case-reed induction. A bank of four forward-facing carburetors feeds through large reed valves placed in the center of the NSR's V, and all four enter the crankcase directly; thus, the location of a carburetor relative to its respective cylin der isn't critical. Another advantage to Honda's design is that the wide V-angle allows the engine to be snuggled
fairly close to the front wheel, contributing to the forward weight bias required on 500 GP machines. One drawback of the NSR500 engine is its abrupt powerband and minimal amount of flywheel, which were very noticeable on the tight, bumpy Laguna Seca circuit. The Honda wanted to break its rear wheel loose over every ripple or slick spot on the track, making life very hard for both Wayne Gardner and his rear tire. We suspect that a crankshaft weighing a few more pounds might have trans formed the Honda's handling at Laguna Seca.
