Honda NSR250V

Honda NSR250V

December 2019

Text and photos by Paul Pearmain, © TYGA-Performance

1997 was a particularly good year for Honda in the world of motorcycle racing. They dominated in GP racing, winning the 500cc crown again, and regained the 250cc championship too. Not only that, they were champs in the WSB, winners at Suzuka 8HRs, TT Formula1, Lightweight TT,  the NW200 and the 250 motocross. You’d think their road bike line up would reflect this racing success but sadly this was not the case. The range was somewhat lackluster, and perhaps most telling, it was the first time in 15 years that Honda no longer listed a 250 sports bike in their catalog. As we all know, Honda were never very enthusiastic about the stink wheel despite building some of the best two strokes both on and off the track. They were instrumental in killing it off in fact.

Despite Honda’s dislike for the two stroke, other makes continued with developing and bringing out new two stroke models in the late 1990s. Suzuki had the VJ23 and Aprilia the RS-250, the latter would even be given an upgrade in 1998 and continue into this millennium. So I think it is fun to muse; what if Honda had chosen to compete with Suzuki and Aprilia? What would the successor to or even the facelift of the MC28 look like? Of course it is impossible to know for sure but we at TYGA wondered what if HRC had made a mini version of their NSR500V GP; an NSR250V for production racing and homologated for the street? It seems logical to us and here is our take.

The NSR500V  was introduced as an affordable racebike for privateer teams in the premier class. The V twin had the advantage of less weight over the fours and proved very successful in the World Championship. HRC had their own factory development versions of the 500V with Okada and Ito riding them in 1996. In 1997 was the turn of another Japanese talent, Takuma Aoki, and he finished the season in a creditable 5th place with his V4 Repsol team mates finishing in 1st, 2nd and 4th and another Honda V4, his brother in 3rd place.

Other privateer riders finishing in the points that year on the 500V were Alex Barros and Loris Regiani in creditable 9th and 14th places respectively. Like I mention above, it seems to us, that there was a golden opportunity for Honda to capitalize commercially with this successful and lightweight motorcycle and Honda could have ordered HRC to make a race replica in the spirit of the RC30 perhaps. The MC28 would make a perfect starting point for such a 250V project, being a V twin with a single sided swing arm with the open side on the right just like the 500V. All it really needed was HRC to give it a restyling, upgraded forks and suspension and an exhaust system and the road bike would take on the persona and attitude of the 500V. Unfortunately, it was not to be and in the absence of Honda making such a machine, 22 years later, we at TYGA decided to do so ourselves.

The first challenge was to find a suitable MC28 to modify. Nowadays, MC28s the World over are in short supply and very expensive. Finding one in Thailand is nigh on impossible. However, we did have a registered MC21 and some MC28 parts, so we decided to use the MC21 as the starting point.

Of course, it is never as simple as it seems when you first start these things, and the first issue was the pro arm swing arm was in poor shape. Our particular one had been covered in filler and then sanded smooth to be used to make the mold for our MC28 swing arm protector. At that time, we considered it pretty much sacrificial but now it is a precious rare commodity. So, with no other pro arm available and with the help of our painter K Pong, he was able to paint it in a flat silver to give an almost perfect factory finish. The hub, on the other hand, was already sorted and was one we had got from GT Performance a few years ago for such a project. GT had given it the large HRC wheel nut conversion which is the same style as the 500V! Frankly, it is strange why Honda did not use this on a production bike. Other makes did such as Ducati, Triumph and MV Augusta.

Next thing was mounting the swing arm to the MC28 frame. The MC21 and MC28 frames are very similar and most parts are interchangeable but not the swing arm pivot shaft which uses different diameters and different bush lengths. With a lot of measuring, comparing, offering up etc, we came to a solution which is simple and reversible. By careful selection of various bushes, spacers and the MC21 pivot shaft, it actually only needs one custom made spacer and no cutting to get it to work and we will be offering this spacer and instructions to anyone wishing to carry out any similar conversion.

Our attention turned to the front end. Although we could have sourced an MC28 front fork set, we like to think that by 1997, Honda would have put an upside down version on their 250 street bike with larger rotors than the NSR250s 278mm ones which had been carried over since the MC18. HRC would probably look to their 250 race bikes for this and so we decided to install an NX5 front end complete with 296 mm Brembo rotors, calipers and master cylinder and a Magtek wheel

For triples, we installed our specific NX5 fork conversion for NSR250s which has the correct offset and ground clearance.

The handlebars are NX5 design but made by TYGA. The bike now has a front end that was worthy of a GP replica, so it needed a similarly capable rear shock. Matt had already prepared an HRC F3 rear shock that had been previously used on his NSR300 and this was installed on the MC21/28 hybrid without the need for modification. For a rear wheel, a 5.00 rear would have been perfect but we had to settle on an MC28 Magtek with a 160 section tyre to give it the extra footprint and presence. To tidy up the rear brake, we installed a TYGA bracket and Brembo caliper. We installed an HRC steering damper to take care of any high speed wobbles and fitted a TYGA step kit to raise the peg ground clearance and to provide a more race orientated stance. The chassis was now complete.

There was a great temptation to go for a 300 big bore kit because, apart from initial investment, there are no real disadvantages over the 250 and much more power everywhere. However, we have to look at the market that such a bike would be sold into and for Japan, it would definitely have been a 250cc for licensing and registration reasons, so we kept the motor stock capacity. That said, it was rebuilt and new seals, pistons and other service parts installed. We finished it off with a few choice TYGA parts such as our carbon clutch and sprocket/generator covers.

Because this is primarily a street bike, we decided to retain the autolube system and this involved quite a few challenges when installing other more race orientated items. One of these was the radiator. The bike has a triple core HRC radiator which was never intended to be installed on a bike with a big autolube container next to it. Luckily, there is just enough space for both and we were able to keep the complete MC21/28 autolube system.

We were also able to install the horn which looks somewhat out of place next to a race radiator but the law is the law, and it comes in handy when confronted with stray dogs and the like!

An obvious NSR500V inspired component is the new TYGA carbon air box which uses as much area under the tank as possible to allow the motor to breath without restriction. The design is based on the HRC MC21 ram air box. However, there are significant changes we incorporated for street use. The ram air system is unnecessary and necessitates radical modification/butchering of the radiator to allow for the front air scoop. The TYGA one by contrast is designed to intake still air under the rear part of the tank and has an large volume and unrestrictive foam filter to be used for street riding. Other practical changes from the HRC race box is an adequate clearance for installation of the full street loom, the oil pump and a 300 kit if required. The air box is provided with custom solenoid stays and has all necessary openings for fuel tap, solenoid harness, throttle, oil pump, choke cables and oil and crankcase breather tubes so that the kit can be installed on a street bike without compromising on these features. The holes can be blocked off for race use and blank plugs are provided in the kit. However, for the purpose of this project we wanted to showcase all street functions, though we did install an HRC throttle with single cable as we had one available and it would be a shame not to use it.

While on the technical stuff, Matt printed out one of his racing dash boards. The digital temperature gauge is a TYGA item and the warning LED lights were custom made by Matt for neutral, oil, turn signal and high beam functions. Typically for TYGA, the speedometer was an afterthought, so much so that it hasn’t actually got one! Maybe we will fit a bicycle speedo later and probably should to make it street compliant. If this were a genuine MC28 with its key card there would be no ignition switch and there would not be an issue with placement thereof. As it is an MC21, we had to relocate the ignition switch to the left side behind the radiator. It takes some getting used to and there is now no steering lock but again if it were an MC28, the key card would take care of security too. Matt modified a TYGA meter stay to take the dash and the bike also has aluminium upper stays for the 250V bodywork, and carbon 2T, lower coil and horn brackets.

The subframe is still stock, I suspect that HRC would consider making a lightweight aluminium version if they built this bike and that is something on the things to do list. However, by retaining the stock subframe and undertray it has focused us on making the other components fit these stock items and in doing so, kept the cost down.

Another NSR500V inspired feature of this bike is the exhaust system. The system on this bike is made to the same successful dimensions of the EXCS-0005 but the chamber cones and tailpipes repositioned in the 500V style. These are connected to silencers of the same design and exterior dimensions of NSR500V silencers. They are of course smaller internally to provide the right power characteristics but the extra external diameter (70 mm. instead of 61 for our regular 2T silencers) provides extra baffling. The large exit tubes hint at a bigger cc than 250cc and reinforce the 500 styling. The silencers are held to the seat cowling using NSR500V inspired carbon stays made by TYGA.

Our history of using NSR500V bodywork on the NSR250 goes back to TYGA Performance’s early days and dumpster diving at Sepang in 2001. Poor old Leon Haslam’s premature entry into the premier class was our gain! Our early attempt was to make something more akin to the V4 and we arrived at our Rossi Nastro Azzurro project styling.

This time around, our approach was more cautious and we tried to keep the 500V fairing as intact as possible while allowing for the proportions and design of the 250 road bike. Frankly speaking, it wasn’t that difficult. The most challenging aspect was scaling down the seat cowling to fit the relatively diminutive street bike. It is only when you get up close and personal with any 500 from this period that you realize how huge they are. It is easy to assume because of the cc, the fact they are race bikes, and that they weigh a little over 100kg that they would be similar in size to an NX5. The reality is bit of a shock and the seat cowling in particular is massive. So much so that for our 250 version we had to cut it into slices front to back and side to side in several cuts until we had a bunch of squares that had to be reduced in size and reassembled like a macabre horror mask. I think you will agree that our designer K Thanet did a superb job of keeping the design features while making the seat about 10cm shorter and 1.5 cm narrower.

The seat cowling still looks large and needs the MC28 fuel tank. An MC21 version of this seat cowling would be possible but the wider MC28 tank suits it and for now we only offer the type here which needs to be installed with an MC28 fuel tank. On that subject, we didn’t have a spare MC28 fuel tank but we do make our TYGA GRP MC28 so no problem there. The fairing was much easier to modify to fit than the seat cowling and the proportions of the 500V upper cowling fit the 250 and no meter stays or extensions were needed. We did make upper stays to support the ears and these are modelled off the real NSR500V versions. The lower cowling was a bit more involved but instead of using an NSR500V lower, we started with a TYGA RSW lower cowling and modified it to fit the upper cowling. We also added 250V style ducts on the side and reprofiled the rear part to be more like the NSR500V race bike.  The front fender in this case is stock NX5 RS250 shape made by TYGA Performance to fit the NX5 forks.

As already explained, the bike doesn’t use ram air but obviously a key styling and distinctive feature of the 500V is its air duct in the nose. Conversely, a street bike requires lighting whereas the race bike does not. It was not a difficult decision to use the air duct for a headlight like we have done on many of our previous designs. However, we were keen to make the light as unobtrusive as possible while providing at least the same illumination as the stock NSR250 light unit. We found by careful experimentation that 3 powerful LED lights could be arranged with a very small opening and achieve this goal. In addition, the light unit does not draw much current or cause much build up. The light unit is held in a lightweight chassis and has a carbon duct at the front to mimic the 500V front air duct. It is subtle but effective.

The rear light is our flat LED unit and blends into the contours of the seat cowling. LED turn signals can be installed. However, our stock rear fender has been cut down so for now it doesn’t have any installed. Similarly, mirrors are provided in the kit and can be installed on the upper cowling or bar end mirrors as seen here can be used instead if preferred. The seat pad is similar in design and profile to that of the HRC NSR500V one and has two layers of different hardness foam. The main difference to the HRC version is the front has a flap which is designed to be lifted and allows for the fuel tank to be removed without needing to remove the seat cowling first which is handy when setting the bike up and checking plugs.

The NSR500V probably has more brochure and team paint schemes than bikes made (22 in total).

However, the choice was simple; it just had to be Repsol! It is true that Repsol is a bit cliché given the Spanish oil company’s association with Honda racing these days. There have been numerous race replicas in the last 23 years. However, at that time, there was only the MC28 and the NSR150SP factory Repsol replicas.

For some inexplicable reason Honda chose to use black wheels and left out a lot of the decals on their factory MC28  version. We tried to correct this shortfall and be as faithful as we could to the team that dominated the class in 1997 (all four bikes in the top 5 of the standings). Takuma being the only twin in the team meant we chose his colours to replicate and we have even included the 24s and the windscreen logo for good measure.

Talking of colours, unfortunately computer and mobile device screens don’t really differentiate between regular and special fluorescent pigments so you can’t see how bright the vivid the shades are on this particular bike. K Pong did us proud as usual and was able to match some factory orange and red for the logos. He painted in the graphics in the same colours to make everything match and left nothing to chance. The paintwork was then sprayed in a special UV resistant and very hard clearcoat developed by Car Kolor which is 15 minutes away from our factory and highly recommended. The result is striking to say the least and will get you noticed. This bike is no sleeper! Frankly, this bike is saying ‘look at me, I’m a racer!’, so any chicken strips are unacceptable and are going to get you laughed out of the café. Best to do a few roundabouts before pulling up for your soy latte!

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January 2020,  Paul's Riding Impression:

Now it is 2020 and things have settled down, there is finally time to take the Repsol for a shake-down ride. First though, we needed to get the bike ready. This involved a fairly intensive Saturday session in the workshop with mirrors and some cool new design indicators wired up and installed as well as install a carbon front coil stay and horn stay to replace the Honda steel ones. There were also a few jobs that we had had to postpone during the initial photoshoot due to lack of time such as bleeding the back brake, getting the rear brake light switch to work (it was seized up) and even replace the front Brembo master. This was brand new but had a scary habit of the lever going back to the bars when wheeled around the workshop. Probably just a seal but it will be interesting to find the cause. A few other tidying jobs were done like making a stay for the radiator reservoir and painting the RS250 throttle housing and RS250 clutch lever. We then did the once over to check everything was tight. Matt kicked the engine over and it fired up right away. Strangely, no normal ‘ting ting-a ting’ from the dry clutch in neutral and very civilized. Jetting was a bit of guess but from the sound and his experience, Matt deemed it worth trying for starters. By now it was dark and time to go home and no time to road test. So that would be Sunday’s ‘job’ (we work 7 days a week around here in case anyone wondered )

Sunday was another lovely sunny day and a bit bright for photos so I waited until midafternoon to go for the ride. The bike was a bit hesitant starting up, but once one cylinder coughed into life, the other quickly followed. It settled down into a smooth tick over though the NX5 race rev counter just sat there shaking the needle at 3k because it doesn’t go any lower. I was thinking, do I lock up and just go for a proper ride or do a short ride up the lane and see how it goes? I was feeling lucky, locked up the workshop, put on my riding gear and backpack with camera and made a plan to head to a coffee shop about 25 km’s away. The route would take me on a mixture of highways and twisty backroads.

The first thing I noticed as I pulled away was the riding position was more like an RS250 than an NSR what with the hard seat and the low bars. I was wondering if I was getting a bit old for this type of stance but I soon got used to it. The next thing was I realized I had forgot to check the tyre pressure, it felt a bit hard and twitchy on the front (later checked and it was indeed at 2.7 bar!) By this time, I was out in the traffic on the highway and I was committed to highway speeds and the NSR accelerated smoothly and cleanly. Ergonomics started making sense now with more wind and the rev counter was now sweeping round higher with every gear change. I had to focus on the road and traffic and the bar end mirrors took some getting used to. I also had to remember the rev counter goes a lot further than the engine would be happy me revving it to, so I kept changes to when the needle was at the top round 11k. I soon arrived at the first set of red lights and I was acutely aware that the bright orange, teal and red race replica was being stared at from every direction. I wished I had my tinted visor so I could pretend I was not looking at them looking at me. The lights turned green and off we went and, being a shakedown, no crazy stuff; steady on the throttle, lots of space between me and the car in front as I don’t want to be jamming on those cast iron discs with brand new tyres.  With every passing km, I was getting used to the bike and more confident. Nothing had come loose or fallen off which is a plus, I was even remembering where to glance to find my ridiculous rear view mirrors, (not that anyone was coming up from behind at these speeds).

The next section was in town and I might as well have been an ambulance sirens on. I was getting stares from school kids and the elderly alike. Way too much attention for my modest personality! I guess nobody else in these parts rides around with a huge fluorescent 24 on the front of their orange vehicle so what do you expect? I was quickly out in the twisty section and the NSR was in its element. The handling was superb and it moved instinctively from one bend to the next, scrubbing off speed was easy and acceleration surprisingly good for ‘only’ a 250. It did have a bit of a stutter below 7k due to being a bit off on the jetting but was crisp enough above that and was not bothered by changes in elevation even with my 93Kg + gear sitting on it. I buzzed a couple of guys on scooters and I couldn’t figure out if their expression was of envy, encouragement, fear or loathing. No matter, the next corner was coming up, so down two and smoothly out, one gear down would have been enough but I wanted to keep the revs up higher where the acceleration was smooth and rapid. I wasn’t taking any risks though and wasn’t really ‘going for it’ not that I ever do these days on public highways. It just isn’t really worth it what with all the street furniture and stray dogs.

Soon enough, I arrived at the coffee shop but there is a nice section after it, so I slowed down acknowledged a group of fellow bike guys outside with a nod  and a wave and carried on. In no time, it was all over and I turned round to go back and buzzed the two scooter guys coming from the other direction this time. I’m still not sure that that expression means. Maybe they love two strokes? This time I parked up outside and opposite the coffee shop so I could keep an eye on the bike from my vantage point at an outside table. Before I could even say ‘make mine an iced mocha’, the place where I’d just parked the bike was now a crowd of guys taking pictures and peering in the fairing to get a closer view of the various features of the bike. I had noticed that the front brake had blown some fluid onto the screen when I parked, so I grabbed some tissue and went back to the NSR to wipe it off before it could do any damage. I was immediately bombarded with questions, how fast?, how many cc?, is the fairing carbon? etc. etc. For sure, apart from me, the MC21 was the oldest one present but the respect and interest shown to this old girl was genuine and heartening. The group spontaneously fell into traditional thumbs up pose for one last shot with the Aoki rep and then I went back to my coffee. The fan boys carried on for a bit and then after they disappeared there was another guy who got out of his car with his family and walked over t take photos etc. etc. Oh yes, this is definitely the bike to take if you want attention.

The trip back home was largely uneventful. I stopped for some more shots as the sun was going down and I think you’ll agree the NSR looks quite splendid in a rural setting. I parked at home and washed off the road dust and chain lube from the orange wheels. I then returned to base under darkness and thought this would be a good test for the headlights. Most of the route back is street lit and it wasn’t until the final lane that I could really tell how much the headlights illuminated. Even though we’ve tested the headlight extensively, I was pleasantly surprised how much light such a small aperture in the front can emit. It was definitely up to the job and I was grateful for modern LED technology. More importantly, I was really pleased how very few issues had arisen from the shake-down ride and how comfortable I was riding it. Strange, that racing crouch and hard seat now seemed normal. Nothing broke; the only thing that fell off was one of those wretched handlebar mirrors (good riddance!) The next thing to do is get the jetting spot on and then Matt can perhaps take it for a proper ride round the circuit.

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January 2020,  Matt's Riding Impression:

Paul had been surprisingly uncritical about the 250V. The points to address were the tyre pressures and the jetting.

Indeed, the front tyre pressure was high, so sorted that. The rear was on the money so no problems there. As for the jetting, from Paul's feedback it was a tad on the rich side, so should be a big problem, but I'd need to get a feel of it myself. The bike crackled into life and away we went. I did the usual run, trying not to upset the neigh bours and yes, I'd have to agree that things weren't quite as crisp as they could be, so back to base, off with the tank and carbs, and out with the brass.

Off we went again, and this time the power was much smoother. No stuttering, just smooth linear power up to the power band, and then a good scream up to 12k. Yep, that's better :-)

Not having to fight with the power delivery means that you can just get on and enjoy the ride. The bars are relatively low, so this is no touring bike. The seat is firm, but I can't say that I actually noticed it once I'd got into the groove. The F3 rear shock and the RS250 NX5 forks at the sharp end did a very respectable job of soaking up the road ripples without being overly harsh, which is the usual case with race suspension. And the front forks/Brembo brake combo is a lovely match. Great control with excellent feel. Certainly not the best setup in 2020, but more than adequate for us mere mortals.

I didn't really give it too much stick through the bendy bits (I'll save that for the track), but it simply took each corner in it's stride. No issues whatsoever. Even the run of the mill tyres gripped well on what are not exactly the best road surfaces in the world ;-) As Paul said, the headlight is well up to the job. So much so that I completely forgot that it wasn't a bought one. Worth all the testing, headaches, redesign, testing, headaches, redesign.....etc.

Overall impression? Hmmmm. We're a bit spoiled when it comes to NSRs, but I'd say that this Repsol Aoki rep is my favorite to look at, and it's up there with the best of our "street bike" builds when it comes to the riding. There's not a lot I'd change to be honest. Maybe some sticky bags for the track test, but that's about it.

NEXT!!!...........