The Honda NR750 was the production motorcycle that used Honda’s unusual oval-piston engine. Honda developed oval pistons to allow an engine layout with more valves than a conventional circular-piston cylinder could easily accommodate.
The NR750’s 747 cc V4 engine used oval pistons, eight valves per cylinder, and two connecting rods for each piston. Its technology originated in Honda’s earlier New Racing projects, which pursued four-stroke performance against two-stroke racing motorcycles.
Honda produced the NR750 in very limited numbers in 1992. Its exotic construction made it extremely expensive and technically complex, so it was never intended to become a high-volume motorcycle. The machine is often recognized by its exposed carbon-fiber bodywork and distinctive under-seat exhaust arrangement.
The NR750 should not be confused with the RC30, Honda’s VFR750R racing homologation model, which used conventional round pistons.