Two Brothers Racing Kawasaki KLX138

Most pit bikes fall into one of two distinct categories: silly slow and scary fast. It seems that when building a backyard ripper, you have to decide at the start if you're going to have a slow, easy-to-ride play bike or a serious, all out racer. Finding a solid machine in the middle of the performance spectrum is rare, but we recently tested a bike that was surprisingly well balanced in this regard. The wizards over at Two Brothers Racing set out to modify a stock Kawasaki KLX110 so that it would be not only competitive but also useable and confidence inspiring, and the end result was a quick little rocket that could hang with the freakishly-fast mod mini bike pack without ripping our arms out.

As stated, the basis for this bike is the popular Kawasaki KLX110, a machine that has become the standard platform from which to build a competitive race mini. While Two Brothers did set out to amplify the performance of the Kawasaki, they certainly didn't do anything to dampen its inherently good handling and comfortable, dialed-in little setup. As a result, the frame was left stock. The bulk of the handling modifications were then assigned to the aftermarket Race Tech shock and Marazocchi fork that, according to 14-year-old test rider and mini bike ace Andrew Silverstein, make the bike a dream to ride. "I loved the suspension on the Two Borthers bike!" Silverstein boasted. "I could flatland a jump or come up short on it, and it still felt great. The bike handled way better than a stock KLX as far as feeling stable and with how fast you could come into corners. The suspension also helped the bike to feel really light; compared to a stock 110 it felt about the same [weight-wise], which is pretty good considering all the extra parts they put on".

Augmenting the killer suspension is two of the best additions that you can make to a stock KLX110: bigger wheels and better brakes. By installing the new fork and an aftermarket Two Brothers swingarm, the bike's builders cleared the way for OEM KX65 wheels and brakes to grace the little pit bike. The result? Even more stability, better high-speed handling and more confidence at race speeds. Silverstein estimated that the new brake setup alone nearly doubled the amount of control that he had over the bike compared to stock, and gave the machine a safer edge over the powerful new engine.

Ah yes, the engine: 138ccs of pure aftermarket juice. Thanks to a larger carburetor, Two Brothers exhaust setup and Takegawa 6-disc clutch, the Kawasaki took on a whole new attitude, one that our test rider labeled as aggressive yet manageable. Up top, the motor pulled hard to the last drop and didn't sign off too early, while the high-up hit stayed smooth and strong. Unfortunately, the highly modified nature of most pit bikes often requires that sacrifices be made elsewhere, and the Two Brothers bike was no exception. In this case, the engine enjoyed fantastic top end performance but suffered down low. Silverstein explains: "The bottom end has a big sputter, but once you get into the top the bike is amazing. Once you get into the power it's really good, and it wants to keep pulling. You have to keep the revs up, though, because if you get off the power it dies out-kind of like an 85cc two-stroke. I think this bike is best on a wide-open track, but on a tighter track you have to work to keep it from falling off the power." The lack of initial power wasn't so much a jetting issue as it was a personality quirk, and this was overcome by simply riding around the problem-keep the RPM high and use the clutch to stay in the sweet spot. Without a doubt, the Two Brothers bike has a lot of muscle, but it's certainly not one of those modified minis that are impossible to control. With the right amount of air pressure the tires can still get the power to the ground-even on hard pack-and the roost-throwing ability of the rear wheel is enough to make you grin. The rest of the accessories are the icing on the cake, from the oh-so-sweet aftermarket pegs and seat to the ever-durable Pro Taper bars. In looking at the parts list, it's obvious that you could spend a lot of dough getting a stock KLX110 to this level of trickery. However, the beauty of pit bikes is that you can take it one step at a time and modify them to your personal preferences and at your leisure. Whether you aspire to build a mild fun-bike or a full-on racer, this Two Brothers Racing KLX138 demonstrates a great place to start-or finish-your own mod machine.

Parts List:
Engine
138CC Superhead +R with a 26mm Mikuni Carb. $1399.98
Takegawa 6 Disc Clutch $287.98
Manual Cable Clutch with Cover kit $353.98
BBR Heavy Duty Output Shaft $169.98
Takegawa 4 Speed Shift Drum $110.98
Two Brothers Racing exhaust $279.98
Two Brothers Racing filter and Bracket kit $39.98
Two Brothers Racing Engine Cover kit $229.98

Chassis
Stock Frame
Race Tech Shock $574.98
Marazocchi Forks $1639.98
KX65 wheels OEM Kawasaki
KX 65 Brakes OEM kawasaki
Sik Tendencies Brake Adaptors $249.98
Two Brothers Racing Swingarm $499.98
Two Brothers Racing Foot Pegbar $199.98
Two Brothers Racing Kick Starter $99.98
Two Brothers Racing Tall Seat Assy. $99.98
Pro Taper Handlebars $64.98
Pro Taper Grips $12.98
ASV Levers $89.98
Two Brothers Racing Brake Pedal $119.98
Two Brothers Racing Folding Shift lever $32.98
Two Brothers Racing Graphics kit $59.98