Honda NR, as exclusive as a Ferrari Testarossa

The Honda NR is an unprecedented motorcycle technologically speaking, unrepeatable, a motorcycle so different that no other brand has replicated or will replicate, a motorcycle out of series, unique, exclusive…

In October 1991, Honda showed its new technological milestone to the world press at an event at the foot of the Alps. Takeo Fukui, chief engineer of the project, in addition to other high-ranking officials of the brand, such as Isao Yamanaka, the person in charge of transforming the NR 500 from the circuit into its street version, were the main hosts.

They were in charge of unveiling their new street bike, the first with oval pistons – let’s call them that, although they are not exactly oval.

The act symbolized the maximum technological expression of Honda and, for this, together with the NR, the most exclusive sports car of the brand was shown off, a Honda NSX, the simile of a Ferrari.

It was the logical step since after abandoning the competition Honda NR 500 project, Honda had valuable experience and knowledge in oval piston engines that they could not take advantage of on a street bike.

The NR with an oval piston 90º V4 engine is the most technological motorcycle of the moment, with a technology unmatched by any brand. It was and is a technological banner.

Not in vain, in addition to the oval pistons, it has gear cascade distribution -like the RC30-, electronic injection, a displacement of 748 cc -the result of curious internal dimensions of 101.2 x 51.6 x 42 mm-, 32 valves, 8 connecting rods and 8 spark plugs.

The Honda NR had 4 oval pistons, 8 connecting rods, 8 spark plugs, 32 valves, electronic injection…

Its maximum power was “only” 125 horsepower at 14,000 rpm, and this was the most criticized point because we all expected much more power. If a 500 could deliver 130 hp, a 750 could have delivered at least the same power.

Fukui himself assured that with a new control unit the NR could offer 150 hp without problems, but that they had preferred a sufficient amount of hp to achieve an engine with thrust, but without exaggeration.

Yamanaka explained the complexity of the oval piston, and the challenge it presented. The pistons had a graphite coating on the skirt, some small projections on their upper face, to compensate for the slight reduction in the compression ratio induced by the lightening of the valves – on their lower face they had a slight spherical hollow.

He also explained the complexity of manufacturing and engineering the three piston rings, with small springs that held them against the cylinder walls. And Yamanaka went on to explain the advantages of oval pistons such as the increase in usable surface to introduce more air/gasoline mixture, as well as offering less friction.

The exhausts with exit through the tail were arranged there only for aesthetic reasons

Tests were carried out with cylinder heads with one, two and even three spark plugs per cylinder, being the one chosen as the one that offered the most benefits. And he also explained that they mounted two connecting rods -titanium- per piston because it offered more rigidity and less weight than placing only one.

Accompanying such an exceptional engine, Honda put the rest with some tailpipe exhausts -for purely aesthetic reasons; Interestingly, the electronic control unit was also in the tail-, 16-inch front rim -the last one that would use it-, inverted fork -the first Honda with this component- and a large single-sided swingarm.

On the hub of the rear rim -which is fastened with a single central screw- there was an inscription to highlight the brand’s pride in its development: “The result of a decade’s perfection”.

But this technological demonstrator still exhibited more muscle thanks to a mixed analog-digital instrumentation, for example, which combined five dials for tachometer, fuel level, coolant temperature, oil pressure and temperature, plus a digital LED display for speedometer and odometer. .

The entire body and fairing were made of carbon fiber to lighten it

This digital screen hid a secret: what the pilot saw was a reflection in a mirror of the real led screen, which was placed behind the instrumentation. This was designed so that the pilot’s view would not waste time shifting focus from the road to the instrumentation, as the reflection offered the same depth of field of view.

But there was even more, and that is that the entire bodywork and the full fairing were made of carbon fiber, to reduce weight, and it was finished off with a windshield dome coated with titanium oxide, which gave it a peculiar iridescent tone.

In the cycle part there was a pair of front brake discs bitten by conventional Nissin calipers, plus a rear disc. A curious detail is that a Pro-Arm system sticker “Advanced Suspension System by Honda/ELF France” was included on the swingarm.

The full fairing featured several air intakes leading to a large 7.5 liter airbox, with the two top intakes, with ducts entering through the top of the fuel tank, being the most striking.

Each Honda NR was built by hand at a rate of three units a day

Also very striking were the side grilles of the fairing in the hot air evacuation outlets of the radiator, in the manner of a Ferrari Testarossa. Everything about her was “exaggeratedly flashy.”

At the presentation of the model, Fukui reported that Honda would manufacture each NR by hand at a rate of three a day, with a maximum of 500 units. They didn’t want to make more. As for its manufacture and sale, he stressed that they would only be made to order; the interested party had to go to a dealer to reserve it, leaving a 25% deposit on the sale price.

They also implemented a strict protocol to avoid speculation and that no one could buy many units, prohibiting dealers from selling abroad. The reservation period for the motorcycle was one year: from October 1991 to October 1992.

With the NR he also broke some other speed record on the Nardo track -Italy- achieving a top speed of 303 km/h in the hands of a certain Loris Capirossi…

Produced in only 300 copies, the NR is a technological display of Honda that in 1992 cost seven and a half million pesetas in our country -then we had a luxury tax of 33%-, about 45,000 euros now.

At auctions they are already over 100,000 euros and their value will continue to rise, since it is a technological jewel unmatched by any manufacturer.

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