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2012 Honda CBR250R Project Bike

Wednesday, January 23, 2013



With the fitment of a Yoshimura exhaust and a custom fuel and ignition timing mapping  as well as VP Racing Fuels U4.4 oxygenated race gas the single-cylinder CBR250R posted impressive engine power gains.
(Top) If you’re use to riding bigger bikes, one of the hardest things to remember when you’re riding the Honda is that you can keep the throttle pinned to the stop in corners while upshifting, too. (Bottom) With the fitment of a Yoshimura exhaust and a custom fuel and ignition timing mapping, as well as VP Racing Fuels U4.4 oxygenated race gas the single-cylinder CBR250R posted impressive engine power gains.
Motorcycle road racing always has, and always will be expensive. But considering the price tag of Honda’s 2012 CBR250R ($4099) the cost to compete and taste the thrill of riding in close formation, bar-to-bar, knee sliding across pavement is dramatically reduced… or is it? We aimed to find out so we went racing.

FROM STREET BIKE TO RACEBIKE

One of the biggest advantages of 250cc racing is how much simpler it is to convert into a racer. Still, having barely enough mechanical aptitude to pass high school shop class, we preferred to leave the wrench turning to the pros: enter Jett Tuning. Owned by long-time mechanic and former factory American Honda tuner, John Ethell, his Camarillo, California-based workshop is a worthwhile choice for all your mechanical needs. He’s thorough, quick, and charges a reasonable rate of $100/hour.

The first order of business was to peel off the street bodywork and replace it with a Hotbodies Racing Race Bodyworks Full Set paired to a windscreen from Zero Gravity. While it is possible to race with the stock plastic, (as long as you remove the mirrors and lighting equipment) why take the risk of banging it up, especially if you plan on riding again on the street. We purchased Hotbodies because it was one of the only manufacturers to actually have the parts in stock, plus it costs less than $600 for the set including shipping. While the quality isn’t as high as other, more expensive brands we’ve used, based on the price, it’s a deal that’s hard to pass up.

With the bike naked, we tossed out the heavy and restrictive stock exhaust and sourced one from Yoshimura. Although it isn’t the cheapest pipe in the aftermarket world, we’ve yet to find an exhaust that offers as much value in terms of price, performance, and build-quality. We also refined the drivetrain by fitting a pair of sprockets from Driven spun by a stronger DID ER2 chain.

It’s all about optimum line selection and holding the throttle on as long as possible when you’re 250cc four-stroke racing.

Because the CBR is fuel-injected, the engine will still run adequately in spite of the added exhaust flow. But since we were aiming to maximize engine performance we fitted a Dynojet Power Commander V with optional Dynojet Quick Shifter Expansion Module (allows for lightning fast transmission upshifts.) The Power Commander allows the engine tuner to alter the fuel-injection and ignition timing maps in an effort to improve acceleration power but make the bike’s powerband smoother and easier to manage, too. While Dynojet has gone the extra mile to develop easy-to-use software, for optimum results you still need access to a motorcycle dynamometer and someone who really understands the subtle nuances of engine tuning. This is where Ethell’s decades of racing experience come into play.

Next up was the chassis. While the little CBR’s suspension works great when you’re commuting to work, at an elevated pace it’s more forgiving damping settings will quickly be overwhelmed. The answer is to replace the stock shock absorber for one from Ohlins. Up front, we poured in heavier-weight fork oil and preload adjuster fork caps that allow for some degree of front suspension tuning based on rider weight.

Brakes are an area in which you should never skimp. So we fitted a wave-style rotor from Galfer with a matching set of stronger biting brake pads in addition to a Galfer Colored Sport Bike Brake Lines kit. Lastly, a pair of Renthal Road Race Full Diamond Grips was installed and we purchased a GPS-enabled Solo lap timing device from AIM.

Tires are the final pieces of the puzzle, so we mounted a set from Pirelli. Up front we ran a full-race SC1 compound Pirelli Diablo Supercorsa (110/70-17) and Pirelli Diablo Rosso II Rear Tire (140/70-17). Keen track day riders and racers might wonder why we ran a Rossi II street tire as opposed to the Supercorsa. The reason is the Supercorsa offers a shorter aspect ratio (60 vs. 70) which makes the rear end of the motorcycle sit lower thereby reducing steering response. And while it may offer a hair more grip it can’t match the street tire’s durability, allowing you to complete multiple race weekends on just one set of tires.

RACING SIMPLIFIED

Originally I was planning on saving my 250 racing experience for a later date, but circumstance led to the bike being available to race on Sunday during Round 8 of the WERA West club racing series at Las Vegas Motor Speedway. Not wanting the bike to gather dust under the EZ-UP, I slipped on my suit and went for it.

Honda’s CBR250R proves you don’t need to spend a lot of money to be entertained on the racing track.

Arriving at the track on race day always presents a unique set of challenges, the main one being bike set-up and actual practice time. Due to the little CBR’s simplicity set-up is limited to checking tire pressure, setting the height of the brake and clutch lever and topping off the gas tank with U4.4 from VP Racing Fuels. Set-up done, check.

When racing with WERA, each class gets two short practice sessions then it’s time to race. Typically that minimal amount of seat time makes it difficult to get up to speed if you’re riding a larger, more powerful motorcycle. But since I was on a 250, two 10-minute practices would be plenty… or so I thought.

Compared to larger, 120-horsepower 600cc sportbike which demands some degree of throttle hand restraint, on a 250, the name of the game is all throttle, all the time. The biggest challenge is how long you can keep the throttle pinned before flicking it into the corner, while using the least amount of braking force as possible.

When you have just 30 horsepower at the back tire everything on track happens at a more quantitative mental pace. The bend ahead arrives a little later and racing within inches of the guy next to you doesn’t seem as risky. Since you don’t have the torque and acceleration power of a big bike, you can’t throttle your way out of mistakes which makes maintaining forward momentum the most critical aspect of the ride. Not only does it force you to follow the optimum racing line, it teaches you to keep every mph of speed you’ve got. It’s these reasons that make 250 racing great for those new to the sport or someone looking for a refresher course in racing.

While proper line choice comes easily, exploring the limits of tire adhesion proves to be more demanding. Based on our bike’s approximate 325-pound curb weight, not to

Riding or racing a Honda CBR250R is a great way to experience the excitement of racing in a safer way.
mention the crazy grip available from the Pirelli rubber, it was a tougher time to acclimate to how much lean angle you could carry through corners as well as how hard you could load the front tire. It also took time to get comfortable riding through corners with the throttle pinned while upshifting into the next gear while your knee puck glides across the road. It’s a surreal experience and enough to make even a more experienced motorcyclist giddy with excitement.

In the next episode of our itty bitty CBR250R project racer adventure we visit Southern California’s Chuckwalla Valley Raceway and mix it up with a 40-plus pack of pesky green Ninjas to see if the little CBR that could can mix it up with its green nemesis.
2012 Honda CBR250R Project Photos
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Jett Tuning - Performance Workshop
Jett Tuning handled the conversion of our CBR600RR from a bent up street bike into a dedicated road racer.
Considering how high-tech modern street and sportbikes have become building a race bike in your garage is trickier than you’d think. Enter Jett Tuning, a Southern California motorcycle turning shop owned by long-time AMA Pro Road Racing wrench, John Ethell. Located north of Los Angeles, in Camarillo, California, Jett Tuning is a full-service motorcycle work shop that specializes in keeping your motorcycle, ATV and side-by-side running in tip-top condition. They also have the advanced mechanical know-how to re-build both two and four-stroke engines and have a Dynojet 250i dynamometer for tuning both carbureted and fuel-injected motorcycles.
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Comments
12345   February 15, 2013 07:29 PM
jfc1, who exactly are you talking to?
motousa_adam   February 11, 2013 08:39 AM
Hey Igor, I just posted it up in the article. As you can see with some mild tuning the engine produces substantially more power... Adam
Igor   February 9, 2013 01:45 AM
Do you guys from Motorcycle USA have the dyno run of the bike before/after putting the exhaust, PowerCommander and going to JettTuning? Aproximate values that you remember if you do not have the graphic of the dyno run Is the graph posted at http://www.jetttuning.com/, the one from your CBR 250R, with 23.95 hp stock and 25.2 at the back wheel and inicial torque of 16.21 and final of 17.07 lb-ft
Piglet2010   January 25, 2013 01:28 AM
If I was running a racing series and wanted it to be inexpensive, I would prohibit any mechanical modifications beyond removing lights and passenger pegs, safety wiring, and swapping bars and pegs for better rider fit. Tires would also be limited to non race-rubber, and no tire warmers allowed (have a warm-up lap and a rolling start).
Piglet2010   January 25, 2013 01:24 AM
So we are looking at about $9K to $10K for this bike - for $12K you can get a purpose built track bike with a 250cc 4-stroke motor from a MX bike that will weight 120 pounds less.
pacman52   January 24, 2013 11:58 AM
Like some others have said... price of the bike plus parts & labor just to give us an idea how much it would cost to make the CBR250R a track weapon... Thanks.
Piglet2010   January 23, 2013 09:09 PM
I would like to see the price breakdown also - maybe an Aprilia RS125 would be a better deal?
guambra2001   January 23, 2013 06:14 PM
Can you guys post the price of all the parts and labor that you guys bought?
neo1piv014   January 23, 2013 06:26 AM
I remember one of the guys on the Kawi forums saying that if you truly think you've "outgrown" your 250 and need more power, you probably haven't taken it on the track yet. I wish I still had my Ninja 250 just to take it out on the track and flog it a bit.