NS500: Technical Data
and Race Review
text＝KIYOKAZU IMAI
translation：SHINTARO URASHIMA
The 3-Cylinder Machine That Built a Solid Foundation for HRC
NS500 Delivers Honda Its First Premier Class Riders' Title in 1983
Freddie Spencer who won his first championship aboard the Honda NS500 in 1983. At the Spanish GP in the photo, he won a one-on-one battle with Yamaha's Kenny Roberts. (Photo/Shigeo Kibiki)
V-type 3-cylinder engine with 120-degree evenly spaced explosions
with a displacement per cylinder of 166.2cc
The V-type 3-cylinder engine of the NS500 was completed within a very short period for a newly created engine. Honda utilized the technology that they had cultivated in the 2-stroke engine for motocross machines. This engine, including carburettors, was painted black, replicating the success of their motocross powerplants/engines. (Photo/Honda)
The NS500 was Honda's works machine run in the 1982 and 1983 Road Racing World Championships. It had a 2-stroke V-type 3-cylinder engine with a total displacement of 498.6cc/166.2cc per cylinder. The bore x stroke was 62.6mm x 54.0mm. Each cylinder was ignited every 120 degrees of crankshaft rotation, which meant the explosions were evenly spaced.
This V-type 3-cylinder engine was mounted on the chassis with the V-shaped valley facing forward. The two upward cylinders (No.1 and 3) and the downward cylinder (No.2) were angled at 112 degrees; the carburetors for the three cylinders were all set up in the valley. The reason why they had chosen this angle was determined by the fitment requirements to the chassis. What is interesting to note is that Honda adopted the 112-degree angle even for the new V-type 4-cylinder engine of the NSR500 after 1987.
They used a Keihin PE carburetor with a forced opening-closing slide valve; the intake system was a piston reed valve. These technologies were cultivated in the 2-stroke engines for motocrossers developed by Honda from the 1970s. Adopting them for the NS500 made it possible to mature it in a short period even though it was a newly developed 2-stroke engine for road racers.
