It evolved from the popular NS250R MC11 and was produced over four distinct generations, each powered by liquid-cooled, reed valve inducted 249cc 90° V-twin two stroke engines.

All engines incorporated the Honda RC-Valve power valve system, and nikasil-sulfur lined cylinder bores (hence the 'NS' in 'NSR').

The road going NSRs were built in the image of the Honda RS250R (also known as the NSR250) production race motorcycle series, although they shared no mechanical parts.

1987 Ignition System: CDI 1987 Swing-Arm: Straight with Rear Brake Lug 1988 NSR250R MC18 R2j1988 NSR250R SP R4j Rothmans MC18 1988 Ignition System: PGM-I 1988 Swing-Arm: Straight with Rear Brake Lug 1989 NSR250R MC18 R5k1989 NSR250R SP MC18 R6k 1989 Ignition System: PGM-II 1989 Swing-Arm: Straight (Rear Brake Arm used, so no lug) The engine is a 249cc 90° V-twin liquid-cooled two-stroke with crankcase reed valve induction via twin naturally aspirated carburetors.

Bore and Stroke: 54mm × 54.5mm The gearbox is a six-speed constant mesh cassette type with multi-plate wet clutch.