When word first leaked about a new Kawasaki Ninja 250, pictures started popping up from Japan of a local tuner's take on the venerable beginner bike. Beet Racing had swapped the standard fairings for race plastics painted in similar fashion to that of John Hopkins ZX-RR MotoGP machine, complete with Hopkins' number 21. It also went on to swap a Brembo 4-piston caliper in place of the stock unit, a titanium exhaust system and a trick-looking prototype reinforced swingarm. Seeing this bike got the wheels in our head turning; what would a Ninja 250 really be like on the track?
Never one to let a good idea go to waste, SR approached Jeff Herzog, Kawasaki's Media Relations Manager, about the Beet bike and if there was any intention of taking these little buzzers to the track. The more we talked it became clear that we wouldn't just be taking a bike to a local trackday. Oh no, we were actually going to enter it in a competition. Herzog, himself a former Ninja 250 racer, liked the idea but didn't know where it would stand a chance in the local club racing scene. It was about this time that the Willow Springs Motorcycle Club announced that it had developed a new class, the Ninja 250 Cup. The premise around the series was to promote racing in the club for as little as possible through extremely limited modifications. And there was the answer we were looking for.
We sent the bike off to Carry Andrew and his Hypercycle shop to get it prepped for its racing debut. Our goal for the project was to build a proper, raceworthy Ninja 250 for $6000, including the cost of the bike. Why $6000? Because that's about the going rate for a decent used 600cc racebike. With the Ninja, one could have a new racebike that could teach the racing craft without the excess speed of a 600 or a 1000.
This aftermarket exhaust,...
This aftermarket exhaust, provided by Area P, was one of the first modifications we did to the bike. It just so happens you'll find it on every bike in the class. Our bike hovered around 30 horsepower just with this pipe and the appropriate jetting changes.
The Nuts And Bolts
Starting with a standard Ninja 250 ($3999), the stock exhaust was the first thing to go, replaced with an aftermarket carbon fiber unit from Area P ($495). To let the bike breathe properly, the ancient art of jetting the carburetors for that perfect air/fuel ratio was in order. Because the little 250 would be screaming at the top of its lungs most of the lap around Willow Spring's 2.5 mile course, proper main jets were the most important piece of the power puzzle. Surprisingly, the jetting is close to perfect straight from the factory, but after numerous dyno runs factoring in Willow's elevation, Andrews decreased the main jets from 98 to 95 with a Factory Pro jet kit ($89.95). The engine now produces approximately 30 horsepower, but more importantly the power curve is much more linear compared to the factory settings. While it may not seem like much, compared to the stock 250 there's a marked difference in mid-range punch as well as top-end power.
Jim Lindemann worked his magic...
Jim Lindemann worked his magic on the stock rear shock and simply added a piggyback reservoir, giving us the ability to adjust rebound and compression damping. This cost-effective solution only cost a couple hundred bucks and kept the rear end nice and planted.
Next, Jim Lindemann of Lindemann Engineering tackled the suspension work. Under the rules the rear shock is allowed to be replaced with an aftermarket unit, while the front fork tubes must stay in place (though internals may be modified). Stock, the Ninjette rear shock is only adjustable for preload, but instead of replacing it for a much more costly aftermarket unit, Lindemann simply installed a piggyback reservoir onto the stock unit for compression and rebound adjustability. This cheap solution proved more than adequate for a simple bike like this. Other aftermarket options available can cost upwards of $1000, but for just a tick over two C-notes the Lindemann route is hard to beat. The simple modification makes a drastic improvement to the rear of the motorcycle; whereas the stock shock is extremely soft, being able to add rebound and compression settled the back end nicely. After some experimentation with a prototype cartridge-style front fork system for the 250 that proved to be entirely too firm, we eventually reverted back to the standard front fork and left good enough alone.
That's it for the go-fast goodies. The next obstacle was making the green bomber look like a proper racebike. To do that, we removed the standard bodywork and replaced it with a set from Catalyst Racing Composites. The kit includes an upper ($289), lower ($226), tail ($189) and front fender ($93). For those really looking to save a few pennies, a catch pan underneath the engine capable of containing all of the engine oil is all that's really needed per the rules. Otherwise, simple number plates can be creatively attached to the front and sides of the bike to please the folks in timing and scoring. After that, little accents were all that remained. Steel-braided brake lines were added front and rear ($70) and Andrews accented the bike with a spare set of Sato rearsets he had lying around. While originally for a '05 Suzuki GSX-R1000, with some slight modifications he was able to bolt them up. Necessary? No. Trick? Absolutely.
The last piece of the puzzle was replacing the stock tires. Thankfully Kawasaki fitted 17-inch wheels to the bike, allowing the use of modern rubber. We chose to go with the Bridgestone BT-090 in a standard 110/70 front and a slightly oversized 140/70 rear. Look hard enough and you should be able to find a set for around $260--money well spent as the tires will last at least three--yes three--race weekends.
Let's Go Racing
With the bike ready to go, we ventured out to Willow Springs last July to see how we'd fare. So what's it like to ride? Well, it's slow. Really slow. But that lack of speed allows the rider to focus on learning track markers and hitting them every time. Racing small horsepower machines also emphasizes corner speed and maintaining momentum rather than relying on horsepower. The key to being successful on the Ninja 250 is keeping the throttle open for as long as you can, maximizing momentum, and staying in the draft. All of which are skills that will come in handy on bigger machines.
Originally we had only planned on making a solo cameo appearance at the monthly Willow Springs Motorcycle Club races. At the start of the first weekend it was clear that the bike had more gusto than a stock 250, but figuring out where we were compared to the rest of the field was still anyone's guess. The answer would come soon after as all the bikes lined up on the grid for the race. The scene as the green flag dropped was akin to a swarm of bees stuck in molasses: all noise and no forward progress. Because I hadn't raced in the class before and therefore had no points I started from the back of the grid. So far this year one man has won all of the Ninja Cup races: Wes Totsubo, so obviously our goal was to beat him. By the third lap we had cleared the rest of the field, leaving only one person to chase. If it was that easy to pass everyone else, catching up to the leader would be easy, right? Wrong. In a series like the Ninja Cup, emphasis lies more on the rider than any other factor and the fact that the bike in front of me was only getting smaller was proof.
To add insult to injury, a sure podium finish was erased when a fellow competitor tried to sneak through for an inside pass. Unfortunately, he leaned the little 250 over so far that the sidestand mounting plate made contact with the ground, lifting the rear wheel and causing him to go down, taking us both out in the process. Game over.
Not wanting to bow out of the series with a DNF, team SR decided to give the race another go in the September round. Experimentation with different lines and braking markers in practice (the word "brake" is used very loosely) put me right in line with Totsubo and in the race it became a three-way battle for the lead between the two of us and another local fast guy, Jeff Tigert. This race would prove the importance of the draft as the leading pack used it to break away from the rest of the field. The entire eight lap sprint was a jockeying match to see who would be in the best position to draft past the leader on the final lap. Coming out of the high-speed turn nine, yours truly caught a draft from the leading bike of Totsubo onto the front straight. As I maneuvered to the left of Totsubo to overtake, he moved left to thwart my advance. With little track space to my left before the dirt, elbows were extended to gain some precious real estate. Totsubo and I made contact no less than three times on the run to the finish line. Meanwhile, Tigert in third place took advantage of the double draft in front of him to edge past both of us and take the win.
After the race, the fourth place rider filed a protest against the SR bike claiming we had an illegal windscreen and a keyless ignition. And while it's an unfortunate way to gain a position in the final standings, we were disqualified from second place during post-race inspection for lack of an ignition switch (the windscreen was legal). Ironically, the rules were later changed to allow the use of keyless ignitions.
By now we had participated in the series twice with nothing to show for it. Clearly not the way we wanted this story to end, we ventured back to Willow again in October. During the race it was the same three-rider battle for the lead. And just like the month prior everyone was jockeying for position, setting new lap records along the way. On the last lap again we were in prime position to repeat the draft move on Totsubo. It was all for naught as we made a mistake in turn five and couldn't make up the gap. Although we didn't win we finally had a second place plaque to show for our efforts.
When all is said and done, racing a Ninja 250 is a barrel of giggles from the word go. The limited modifications allowed makes for a level playing field with a minimal cash commitment. Tires last for weekends at a time as does the fuel. Better still, the competition is tight no matter where you are on the grid. But best of all, we still managed to stay under our budget; you can build a bike similar to what you see here and still have a Benjamin Franklin left over. If there was ever a way to go racing on the cheap--this is it.
The updated version of the Kawasaki Ninja 250 along with the recent spike in gas prices has brought a resurgence to the small-bore motorcycle market. Ever ones to jump on the little bike bandwagon, for 2009 Aprilia is bringing its RS125 two-stroke here to the states. One caveat: it's not road legal, meaning that if you want to spend the $5499 it takes to get one then you're probably not hurting too badly from this economic downturn. But back to the bike; design cues come directly from its grand prix racing cousins, even down to the "Spain's No. 1" livery that graced Jorge Lorenzo's 250cc championship-winning machine in 2007. Power comes from a single-cylinder, liquid-cooled 125cc two-stroke engine with a separate lubrication system (meaning no premixing of the fuel and oil). Bringing the bike to a halt is a single 320mm rotor clamped by a four-piston, radially-mounted caliper.
While not legal for road use in the states, these little flyers are rampant in Europe due to the tiered licensing system they use. As such, the RS125 makes some concessions to meet the demands of street riders, while keeping as much of the racing heritage as it can. For instance, the bike has an electric starter. The front fork is an inverted unit with no adjustability, and the rear shock is only preload adjustable.
That said, it's much closer to a true racebike than the Ninja 250 will ever be. Both make about the same power (albeit in much different fashions) and with a dry weight of just 280 pounds the Aprilia should have a distinct advantage in handling. We had the opportunity to sample the RS125 at a Fastrack Riders (www.fastrackriders.com) trackday at Willow Springs and the differences were immediately noticeable. Being a two-stroke, the 125 goes nowhere until the engine is spinning near redline. Only then can the clutch be feathered out. Once moving, the six-speed gearbox is smooth and positive. This is good because you'll be shifting often to keep the bike in its narrow powerband. The huge brakes are almost too much, but it never overpowers the rest of the machine. One finger braking is easy with the clamping force the four-piston caliper provides.
Flicking the bike from side to side is where the weight difference comes in handy. At the mere thought of direction change the RS125 will move where you want it to go. This weight advantage also helps in acceleration, as it gains speed quicker down the front straight than the Kawasaki. The suspension, while basic, performs admirably. The damping rates are geared more towards street riding (meaning soft), but provide adequate compliance on the track.
Overall, the Aprilia RS125 makes a very competent (and fun) track toy. But that's all it will ever be. It's not street legal here and there are no racing classes for it. Besides, if two-stroke racing is something you'd like to try then a true, dedicated racebike will suit your needs better.