From time to time, stories surface about motorcycle models that never quite made it to production. Yesterday, one such case caught the attention of enthusiasts—a seemingly genuine brochure appeared online for a never-released prototype: the Honda MVX400F.
Information about the bike is scarce, but a quick Google search reveals enough fragments—many from translated Japanese sources—to piece together a broader picture. In the early 1980s, the motorcycle market was undergoing significant change, and the circumstances that led to the MVX400F’s cancellation likely paved the way for the eventual NS400R.
The brochure focuses heavily on the 400cc class, which at the time represented a vibrant segment of the Japanese market—reportedly worth 79,690 units per year. Honda’s marketing case for the MVX400F was clear: the company wanted to strengthen its presence in this crucial category by offering a large-capacity two-stroke model to complement its existing four-stroke line up, including the inline-four CBX series and the V4 VF range.
With the addition of the MVX400F, Honda would have been able to offer a 400cc motorcycle for every type of rider—two-stroke or four-stroke—ensuring broad appeal in Japan’s most competitive displacement class. The prototype carried the internal model designation NC14, marking it as a close relative of other innovative Honda projects of the era.
Brochure translation
firstly apologies if it reads a bit weird, but the translation via an old scan via google translate, but you will be able to understand where Honda was with the model.
Introduction
As you know, the 400cc sports bike has been an entry-level bike for people since the license system was introduced, and can also be considered a high-performance bike. Its customers are mostly young people (men around 20 years old), and super sports types are the mainstream. Therefore, each company is introducing a number of the latest models in this class equipped with cutting-edge nanotechnology and various devices. Honda has released the CBX400F with an inline 4-cylinder engine and the VF400F with a 4-cylinder engine. Both have been popular and highly acclaimed for their performance and technology. Looking at the actual figures for January to March 1983, the price of 2,000 yen shows the wide range of the market at that time. These are Honda's popular models.
1982 400cc Super Sports Registration Stock: 79.690
In addition to this, we will introduce the MVX400F equipped with the 7401 V-type engine, which is a standard water-cooled 90V D type engine, which has been featured in the Road Racing GP. This machine has a sharp design with a sharp finish. It is designed to achieve the best performance with a spirit of event.
Trends in the 400 Supersports Market over the Last Five Years
Market needs
Needless to say, the 400cc category is dominated by super sports bikes. Our customers are mostly in their teens and early twenties, and are keen on high-potential technology. Their image is of a machine with the most powerful, super-performance qualities, with a racing concept. However, at our club, the young generation, who make up the bottom half of our customers, are looking for a bike that is lightweight and easy to ride, as they are more likely to ride with a high-performance bike.
However, we must never forget that these people are riding machines that fully utilize cutting-edge technology and mechanisms, and that they can enjoy riding them. It is important to understand their desires and make the characteristics of the MVX400F, which has high performance and high mechanics based on a unique concept, low movement, is lightweight and easy to handle, and has good sponsorship, a selling point.
Aim of development
In a word, it is an "NS Replica", that is to say, the engine is a high-powered water-cooled mini-cycle V-twin engine that inherits the same concept as the Honda Power Racer NS500, which has been winning consecutive races in the road racing GP500 class, and its 400cc capacity makes it even closer to the NS500. Furthermore, by mounting this engine in a lightweight, compact frame body of the 250 class, it is possible to fully utilize its intense power.
The peakiness that is common in conventional 2-stroke engines, and the lack of. Unlike the previous model, it has a wide power range that can be used from mid- to low-speed ranges, and the flexibility at high speeds that is unique to Qigong.
In other words, just as the NS500 overturned the concept of a GP racer by surpassing the conventional concept of a simple pedal-powered racer, the MVX400F also pursues sweet, sharp response and performance that shows its true value not only when going straight but also when cornering, and will beat other cars with its high fighting power due to its total balance.
Selling points
- A world first! Equipped with an innovative 2-stroke V3 engine.
- The most exciting 400 Super Sport racer concept
- A V-type gasoline machine that is closer to the NS500 concept
- The high output of the engine and the small, lightweight body of the 250vv bike make this a great choice.
We have a weight ratio that is the same as the NS500 concept car. Not only does it have the same peak power, but it also has a sharp throttle response from the mid-to-low speed range, and good acceleration at high speeds, making it easy to use and high power. Moreover, the mass is balanced (W+W 2W), making it theoretically possible to achieve this.
Accessories that expand the world of riding with the MVX400F
Cowling that creates a racer image
- Centre cowl - These aero parts are full of racing spirit (radiator side covers)
- Under cowl - This is an aero part that further enhances the body line (Belly pan).
- Sports cowl - It is a sporty cowl that evokes the image of a single seat.
- Knuckle cowl - side covers for the nose fairing
- Silencer case - Storage compartment for small items that give the appearance of a rear silencer.
- Rear Carrier - A fit suitable for sport machines
- Tag Bag Soft -
- Body cover - bike cover
END OF TRANSLATION
Timeline
1982
Honda began development of the MVX250F, a lightweight two-stroke sport bike designed to compete directly with Yamaha’s RD250 and Suzuki’s RG250. At the same time, Yamaha had already started work on a much more ambitious project that would eventually become the legendary RD500.
1983
Honda launched the MVX250F, a technologically advanced 250cc two-stroke featuring a unique V3 engine layout. Following the success of the NS500 in Grand Prix racing, Honda sought to capitalize on that momentum by developing a larger two-stroke road machine—the MVX400F, intended to be the company’s biggest production two-stroke.
Meanwhile, Yamaha changed the landscape of the performance motorcycle market with the introduction of the RD500, a V4 two-stroke inspired by Kenny Roberts’ championship-winning GP bike.
1984
The pace of innovation in the race-replica market accelerated rapidly. Yamaha released the RZV500R, a lightweight, alloy-framed version of the RD500 built specifically for the Japanese domestic market. Suzuki entered the fray with its own GP-inspired machines—the RG500 and RG400—further intensifying competition in the high-performance two-stroke segment.
However, the MVX250F’s commercial performance fell short of expectations. Sales were modest, and the engine suffered from a number of reliability issues, undermining confidence in Honda’s new two-stroke platform. Compounding the issue, Honda already had another 250cc two-stroke in advanced development—the NS250R, a more refined and competitive V-twin design. As a result, the MVX250F was quietly discontinued.
Faced with a rapidly evolving market dominated by high-spec GP replicas, Honda recognized that the MVX400F would likely be outclassed by the new generation of bikes from Yamaha and Suzuki. The project was subsequently cancelled before reaching production.
In the aftermath, Honda redirected its efforts toward developing a true GP-replica road machine. Having just won the 1983 500cc World Championship, Honda decided to channel its racing expertise into a new project—the NS400R.
It has long been believed that the NS400R’s engine originated as an enlarged and improved version of the MVX250F’s V3, featuring increased displacement and the addition of Honda’s ATAC (Auto-Controlled Torque Amplification Chamber) system. While this remains largely accurate, new information suggests there was an intermediate stage in this evolution—the MVX400F—bridging the gap between the MVX250F and the final NS400R.
There are also references on several Japanese websites to an MVX350/400, which raises some interesting questions. It’s possible that a 350cc version was intended as a rival to Yamaha’s RD350, though it’s unclear whether this was an intermediate stage in development—with displacement later increased—or simply a matter of mislabelling, with “MVX350” and “MVX400” referring to the same prototype. What we do know is that the later NS400R had an actual capacity of 386cc, and even a 373cc variant was produced for the South African market—around 50 units—which used NS250 pistons.
Intriguingly, there’s also a minor reference online to an MVX100 with a V-type engine. If true, that would have been something very special indeed—though it’s far more likely to be another translation error or misunderstanding that’s crept into online archives over time.
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| a colorized version produced by a Japanese magazine |
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| The V3 sensation is even more exciting, the stunning super sprinter 400! |
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| The concept is one step closer to the race track |
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| add on '4th'exhaust silencer for the 250, is actually storage but is shown on the 400 |
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| The NS400R one of the 2 stroke 'holy trinity' |
