HONDA NS400R
A triple treat!
There’s nothing quite like the excitement you feel when a high-performance two-stroke comes on song and propels you out of a corner on a wave of power. More so when it’s a rare example of factory-made exotica: I’m riding an NS400R, the bike that Honda produced in the Eighties to offer the average rider a taste of what the Grand Prix racers were experiencing at the time out on track. Along with Yamaha’s RD500LC and Suzuki’s RG500, the NS400R represented the pinnacle of two-stroke development for road bikes before emission legislation effectively outlawed them. In the three decades since they were produced, these three machines have attained almost cult status as the first so-called race replicas. It is little wonder they’ve attained the status they have: the two-strokes were more easily accessible, manageable and though pricey at the time, nothing like as stratospherically expensive as any sports production or homologation machine since. Better still, you could also ride them to their limits on normal roads without terrifying yourself, or having to limit the experience to a road-race circuit. So here I am on an NS400R, a beautiful minter that with just 1500 miles on the clock looks like it’s just been wheeled out of the showroom. I approach another corner and the bike responds to my touch quickly and holds its line securely. It’s no bigger than a 350cc twin but with three cylinders the Honda offers a more nasal drone as I power out using its useful mid-range. Then it reaches its sweetspot and takes off as the revs hit 7000 and the engine becomes more directly connected to the twistgrip. It’s like coming out of a fog into a world of sunny clarity and the NS400R sings along smoothly at speeds I’d dare not check on the instruments inside the tiny fairing. You can snick up and down the crisp six-speed gearbox to keep it in the power-band and the disc brakes pin it down positively. Gorgeous! Enough has been written about the NS400R, much of it in CMM, that I’d only be repeating what’s on the record. Suffice to say that a stock NS400R handles beautifully, even against modern machines, and provides a riding experience that cannot be replicated by almost any other machine.
Yes, of course the 500cc Yamaha and Suzuki road bikes were more ballistic in their approach, but the 387cc Honda somehow matches what the factory achieved when it won its first 500cc world championship with Freddie Spencer in 1983 by using a more compact three-cylinder machine developed using motocross ideas for the engine and chassis. Wieldier and more manageable than the potent works V4s, the Honda enabled Spencer to run rings around aces like Kenny Roberts. Such is the legendary status of these two-stroke road bikes that they are now fetching what would have been regarded as silly money only three or four years ago. While an NS400R in good condition would sell for just over £5000 then, it will attract offers of double that now. Owner Owen Cashin reckons his spotless NS400R is worth £10,000 now. This is despite what many have said was a flaw: why was the NS400R not a full 500 as was expected back in 1984? One theory is that the needs of Japan’s domestic bike market took priority. In Japan the competition in the 250cc and 400cc sectors was cut-throat with each manufacturer offering a bewildering selection of machines. While Honda had been persevering with its four-stroke singles and twins, Yamaha was clearing up with the 250cc and 350cc LC twostrokes. In answer, Honda offered the VT250F, a high-revving DOHC V-twin four-stroke with 35bhp. Perhaps buoyed by the success of the 500cc three-cylinder racer in 1982, its first year of competition it developed a 250cc two-stroke triple, the MVX250F for the home market. While the racer’s engine had a single crankshaft with two vertical cylinders and a centre one pointing forward, much like the 350cc DKW racer of the 1950s, a layout that enabled the two upper exhaust pipes to tuck under the seat, the road bike’s was the other way round, with two-cylinders facing forward and the centre one upright. Capacity was 249cc and peak power was a class-leading 40ps at 9000rpm. Looked at another way, the MVX250F was a V4 with one of the cylinders missing. Despite an under-seat pipe, styling was decidedly un-racy with a small bikini fairing, rather like the UK’S MBX125, while the steel tubular frame was much the same as the VT250F’S. Few were sold outside of Japan, which was just as well as the MVX250F had some engine problems; most likely because of the way the designers had tried to reduce engine vibration. It was quickly replaced by the much more successful NS250 V-twin in 1984. When Honda’s engineers looked for the basis of the ‘Spencer replica’ the pressure was on. Yamaha launched its amazing RD500LC V4 at the Paris show at the end of 1983, just as the layout of the Honda prototypes were being decided. The MVX250F was the best option, and luckily they took all that was good about the bike and binned the rest. That left the engine, which was modified with a bigger 57mm bore and 50.6mm stroke giving 387cc. Honda might have made the capacity bigger but with the domestic market in Japan having an effective 400cc limit for the average rider, the smaller size was better for marketing, and for other markets it took the heat off the bike being directly compared with the Yamaha. First hints in the UK that the NS400R was on the way were leaked to the press in April 1984, about
the same time as the RG500 Suzuki, and both made their European debut at the Cologne Show in the following September. Apart from the derivation of the engine, the NS400R was completely new. The engine featured the same horizontally-split crankcases and built-up crankshaft with the three big ends in line. All three pistons and connection rods were identical, the vibration issue being overcome with rubber engine mountings. Primary drive was by gears on the right to the conventional multiplate clutch and six-speed gearbox. The three cylinders had liquid-cooled jackets with their temperature controlled by the radiator featuring a fan on the right side. Induction was through reed valves fed from a bank of 26mmventuri flat-slide Keihin carburettors facing forward between the cylinders and an air-box under the front of the fuel tank. Novel means were used to squeeze in the expansion-chamber style exhaust system. The two lower pipes curved forward before looping back on either side, capped by end cans. The upper pipe looped up and down inside the bodywork before exiting on the right. Items like the battery and electrics were protected by insulation blankets. For its capacity, the NS400R was pretty highly tuned, with a claimed peak power of 72bhp at 9500rpm. To achieve this without sacrificing flexibility, Honda used an automatic exhaust tuning system, but it was unlike the Powervalves adopted by Yamaha, which effectively varied the exhaust port timing. Honda’s was called Auto-controlled Torque Amplification Chamber, or ATAC, which changed the resonant frequency of the exhaust pipes for the two lower cylinders. This was achieved by adding extra volume to the pipes with the chamber next to the exhaust port. At revs below 7500rpm a rotating valve
opened to connect the chamber, improving torque at the bottom-end. An electrically-powered solenoid connected to the ignition, shut the valve above 7500rpm to enable the exhaust to lift the power at the top-end. Even with ATAC though, the NS400R was still peaky. After kick-starting, it idles with a sharp crackle from the pipes and if you’re in town you’ll be happy with the pick-up, but on an open road, the engine still needs to be revved to give its best. The exquisite handling is provided by a chassis that was cutting edge in 1984, with an aluminium alloy cradle frame (a first for a Honda road bike), cast-alloy rear swingarm and conventional telescopic forks with spring preload adjustment on the tops of the legs. At the rear, the shock controlled the rear wheel through a rising-rate linkage, while the spring’s preload was adjusted with a hydraulic piston at the top connected to a bezel beneath the right-hand side panel. With a wheelbase of 1385mm, the bike is tiny but doesn’t feel at all cramped. The brakes, with twin discs up front and a smaller single rear, featured dual-piston calipers. As was the fashion at the time, features to minimise dive under braking were used, Honda’s being called Torque Reactive Anti-dive Control (TRAC) in which the right-hand caliper rotated under braking to close a valve to stiffen the fork’s damping. I can’t say it had much effect. Wheels were the updated Comstar design also used on the V4s launched in 1984, using bolted-up sections. For the time, the rims and tyres – 100/90 x 16 and 110/90 x 17 – were skinnier than some but for the bike’s weight, 163kg dry or 183kg wet, they were probably just right. Nowadays they look skinny, but wider rims from other Honda models of the time are easily fitted.
The NS400R was probably heavier than necessary, but then it had a remarkably high build quality, with brilliant fit for all the bodywork items. The exhaust system features a lot of sound deadening which adds weight, and likewise offers owners a route to performance improvement. Against Suzuki’s 95bhp RG500, which was at 154kg dry some nine kilos lighter than the Honda, the NS400R is bound to struggle. When the Honda topped out at almost 130mph, the Suzuki would fly past to reach almost 150mph. But that wasn’t the point, and is less significant now. Some might view the NS400R as a more of a rival for Yamaha’s 347cc Powervalve RD350LC, with a difference of only 30cc in capacity. But the Yamaha with a top speed of 119mph was nothing like as quick, though it was at £1695 much cheaper to buy in 1984. Supplies of the NS400R were limited, with just 300 of the 11,000 produced coming to the UK. Roger Etcell, sales manager at Honda UK at the time and now working for auction house Bonhams, says: “The NS400R is now a real collector’s bike. It was first sold in the UK in 1985 as the NS400R-F in both the red/white/blue (200 units) and also Rothmans colour schemes (100 units) at £2899. It stayed in the UK range with the same spec through 1986 in just the Rothmans colours only at £3199 and finally 1987 at £3299, when stocks were finally exhausted. The NS400R wasn’t a big volume or fast seller, mainly due to its price (same as a CBR600F in 1987). Honda was really a four-stroke brand so some customers were not convinced and often asked why it wasn’t a full 500.” Commenting on the NS400R Hondas he’s seen in his work for Bonhams, Roger says: “I’ve seen just a few NS400RS up for sale in recent times all at close to the £10k mark. I guess that’s what they will be now due to their rarity and technical interest. We’ve only had three come Bonhams’ way in past 10 years with results that show how the prices are on the rise: in 2008 one sold for £2300, another in 2011 for £2990 and in 2012 one sold for £3680. I think if we had a very nice original one for this year’s auctions we would place an estimate of £6k to £8k to entice buyers but potentially expect north of £8k with buyer’s premium.”