“PROSPEC” explained by Matsuda

NSR250R Mania “in a nutshell” (1) [first part]

Hi there, my name is Matsuda. My main occupation is working as an editor for Young Machine, but my passion for the NSR has become so much so that I decided to go about producing a special edition magazine called “PROSPEC” on the side. In this PROSPEC edition, aside from how the bike rides I have been curious to explore the outcomes in production of this series. Consequently, this could have easily turned out to be an impossible to understand edition for pure anoraks, so instead the purpose here is to “offer a rough background about the NSR to those people who are not so well informed”. I will do my best in making the NSR as easy to comprehend as I can. Thank you for taking your time to read this.

1. Methods in distinguishing between NSR “models” [first part]

Amongst the NSR250R models that were offered for sale between 1986 and 1999, generally speaking there are five types that can be classified. In this first part edition I will start with explaining about the three models from the first generation MC16 model to the 1989 MC18 model.

MC16 (1986 – 1987)

NSR250R MC16

The first generation NSR250R model is the MC16. This NSR is equipped with a water cooled two-stroke 90 degree V-shape two-cylinder 249cc engine, and holds the same fundamental structure as the very last model that was released (This is just as a general guide, seeing as the contents regarding each model varies considerably). In contrast with the later year models, it is the earlier ones that are more distinctive and have stronger characteristics. Below is a section with identification points at a glance.

  1. Three spoke wheels (later models are six)
  2. One-sided two-pot caliper (later models four-pot)
  3. Square tail light (later models are round twin lights)
  4. 39mm upright forks (later models are 41mm)
  5. Twin spar aluminium tube “目” frame (This Japanese character means eye and represents the shape of the frame)

The functional aspects of this series is how it is the only engine to be solidly mounted, along with footrests that are rubber mounted. However, there are many NSR bikes that have been turned into customs or have been broken down into parts, so the most reliable thing to do is to look out for the marking on the MC16 frame. If you can see the Japanese character “目” shape on the twin spar aluminium frame, then you know it’s an MC16.

If there is a partition placed inside the frame that heightens the rigidity of the rectangular aluminium material, then without hesitation it is the twin spar “目” (Japanese character for eye) style. This is a characteristic found only on the MC16 model.

Incidentally, there were around 20,000 MC16 units produced, and records show there are only around 3000 remaining now, which makes them pretty rare. However, apologies in advance to the good people who own this bike, but these days one cannot say that this is the NSR model that everyone raves about. Popularity for the earlier models is strong, but the reason it doesn’t apply for the NSR MC16 is probably because the bike released in 1988 is a complete and utter legend.

MC18 (1988)

NSR250R MC18 (1988)

This is the NSR that everyone came to know as “the biggest legend”. With its first appearance coming a mere one year after the MC16 it shares very little in common due to reforms made to the engine, frame and suspension area. It is the NSR that made the biggest impact, the MC18. It would be fair to say that NSR models following this were all connected to the fundamental structure of this accomplished 1988 machine. The reality is that most of the parts on this bike are compatible with later year models. The characteristics of the 1988 model are quite something else…

  1. Six spoke wheels (rims widened)
  2. Four-pot front calipers
  3. Front forks widened to 41mm
  4. Rounded shape tail lights
  5. Miniaturised square shape headlight
  6. Pentagonal section frame

At this point I would like to say that any common points with the MC16 are virtually non existent, and also ask that you give your attention to the identification mark on the frame that detect the 1988 machine. The Japanese character meaning eye “目” from the MC16 twin spar frame is ever so slightly altered making it a five sided shape, and this is what characterises the MC18.

Upper section of the MC18 (1988) frame. The angle on the upper surface is dropped in a slant making it a pentagonal section frame. According to a specialist, it seems that changing from a four-sided to a five-sided twin spar frame gives birth to greater flexibility.

The reason that the 1988 model became so legendary, is that for the time it was loaded with gizmos that made it ride well, so the threshold for demands in technology were heightened. Also, such features as being able to remove the power limiter ridiculously easily surely added to the appeal. The catalogue description noted how there is a tentative independent regulation of power set to 45bhp. Nevertheless, by pulling out just one bit of wiring from inside of the tail cowling area, the device (called the RC bulb on NSR models) regulating the high revving divergence would fully open, and as a result just shy of 60bhp showed up at the rear wheel! In other words, one can say that in reality this bike was only ever a 60bhp machine that had been regulated from the start. Incidentally, no speed limiter was ever fitted.

One more point worth mentioning is how the 1988 NSR model runs an innovative “PGM system”. This system controls things through a computer like firing up the engine, the carburetor, the RC bulb, and the oil pump. Consequently, it is precisely this mechanism at the heart of the bike that caused this NSR to be the fastest. What made the NSR so fast was how this computer controlled two-stroke engine handled power at low speeds smoothly, with its silver lining being at high speed. From then on the NSR evolved with the PGM, but of course its origin lays with the 1988 model.

Incidentally, there was also an SP version of the MC18 equipped with magnesium wheels that was put in production worldwide. One could say that out of all of the NSR models this Rothmans colour scheme 1988 SP is the killer! One should think of the spec in the same way as gaining the top winnings in a game of Monopoly!

What stands the 1988 NSR further apart from the rest is the Rothmans SP. Much in the same way as Batman or James Bond still manage to impress us today, this is a machine that is a sure thing to be proud of.

MC18 (1989)

NSR250R MC18 (1989)

Out of all of the 250 models that were sold, the number one shining star was certainly the unparalleled 1988 MC18, but other rival makers were criticising it for being too much of an extreme bike. Therefore, the 1989 model changes declared “a power curve” that would aim to lessen the extremity of the bike, and change the engine characteristics by spreading out the torque band, making it easier to handle. The power curve of the 1989 model also measured brilliantly on the dyno, and leaving aside terms of actual performance you could still feel a great buzz similar to the power of the fast 1988 model. Having said that, if one removed the limiter on the 1989 (Despite being harder to remove than the 1988 limiter, even so it was still relatively easy) version this is when the clear difference showed up, as the standard 1989 model could not be considered to have the same chatacteristics as the “absolutely legendary 1988 bike”.

Fundamentally, there are only minor changes between the first and second versions of the MC18 models. Despite going without a huge amount of modifications, the identification points in appearance are as follows.

 

  1. Front cowling gets a slanted nose
  2. Silencer mounted higher up
  3. Rear wheel gets a wider rim
  4. Rear caliper gets floating mounts
  5. Pillion pegs are stowed away
  6. Swingarm is turned into a pentagonal section shape

These were the main changes made. In terms of big design characteristics of the 1989 version, some unnecessary distinctions were made after switching to an external combustion chamber. Also, the front of the seat on the 1988 model has three shark fin looking ducts that are not to be found on the 1989 model, which can be used as a comparative identification point. As expected though, the clincher with this bike is the frame. Although the fundamental form was handed over from the 1988 model, the 1989 model has a floating rear caliper and opens up a gap where the torque rod clings to the upper part of the right-hand side swingarm pivot. You can spot this all in an instant.

Distinguishing between the 1988 and 1989 frames involves taking note of the brake torque rod that sits on top of the right-hand side swingarm pivot. The 1989 pentagonal swingarm is also an identification mark, only that because parts get changed about so frequently it can be a little tricky knowing which year a bike truly is, especially from the 1990 MC18 onwards which has the fairly regular nickname of “Gull Arm” appropriated to it. One other characteristic of the 1989 model is the updated wing mark design on the fuel tank.

The fundamental aspects of the PGM system (2) evolved to increase sophistication further. The 1989 model was cast in the shade a little bit by the 1988 model, nevertheless, it made record sales as the number one selling 250cc bike for two years. Moreover, as expected the additional SP model is the killer bike out of all of the NSR models with its dry clutch. It is because of the 1989 model and its ‘jingle, jingle, jingle’ resonance of the clutch plates that shake the hearts of street racers. Incidentally, throughout the MC18 models of 1988 & 1989 over 45,000 units were produced, with 10,000 recorded as being in existence today. Well, this is as far as the first part will lead us. I will pretend that I haven’t realised how the content is gradually becoming more and more distant from the aforementioned “easy to understand” and “in a nutshell” promises made, and will leave introduction of the remaining two bikes for the latter part of this article.

マツ

マツ

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「西部警察」と「北の国から」をこよなく愛する本誌編集部員。NSR専門誌・PROSPECのほか、フリーペーパーとして復活を果たしたビッグマシン零(ゼロ)の編集長も兼任する。
■1975年生まれ
■愛車:HONDA NSR250R(1992)/HARLEY-DAVIDSON XL883(2009)

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