BBR DR-Z160 - Dirt Rider Magazine Online

Immediately after Ricky Carmichael rode into the record books with his second perfect outdoor motocross season, he took a much-deserved vacation with his wife. He had spent the summer training and racing his way to 24 moto wins aboard a Honda CRF450R, plus he had the added stress of his preseason announcement that he was leaving Team Honda for Team Suzuki. With little time to spare, RC came right back to California to begin testing for the U.S. Open and his much-anticipated return to Anaheim's Angel Stadium, where he'd be facing the defending champ, Chad Reed, as well as James "Bubba" Stewart, Travis Pastrana, Kevin Windham, Mike LaRocco and, possibly, Jeremy McGrath. RC has had a lot on his plate, and his winter will be all work, so we took it upon ourselves to break in his factory Suzuki for him.While Carmichael unwound, we thrashed his ultratrick four-stroke with its works-grade suspension and wheels, a handmade aluminum fuel cell, a heavily breathed-on engine, one-off triple clamps for improved steering and the familiar No. 4 on unfamiliar yellow plastic. Better yet, we rode the factory version of a bike that has yet to be released to the public, whether American, European or Japanese. How cool is that? Dirt Rider slung its collective leg over the gripper saddle of RC's works Suzuki. Not the RM250 he'll be riding in supercross or the RM-Z450 he'll campaign outdoors, but the BBR Motorsports DR-Z160 he'll be cruising with in the pits.Aluminum-Perimeter FrameThe Boys in Black commenced work on the KLX/DR-Z110 frame the instant they finished their previous project, an aluminum-perimeter frame for the CRF/XR50. With the Honda 50 frame kits, the main concerns were smoothing out the twitchy handling and beefing up the chassis for long-travel suspension. Being larger and heavier, the Kawasaki KLX and Suzuki DR-Z110 aren't directionally challenged, but they do weird things when the suspension and motor are heavily modified. The stock frame flexes when travel is extended, and the brakes are taxed when the engine is tweaked. BBR developed an extended swingarm that is 2.5 inches longer than the stock arm and uses an Elka remote-reservoir shock. However, the Super Pro swingarm kit (with billet shock tower) and Marzocchi 35mm inverted fork kit (complete with clamps, brakes, wheel and tire) placed such stresses on the frame that the Brown brothers decided to develop a full-on frame kit for the mighty midsizer.Although overall size is closer to the Honda 50 than the CRF150F, BBR chose the 150-size aluminum side spars for as much 110-mandated stiffness as possible. Starting with a slab of 6061 billet aluminum the size of an old-growth redwood, the company machined out the steering stem, footpeg mount, engine cradle and swingarm pivot. As with the Honda 50, the footpeg mount and perimeter spars actually create a semi-cradle for the engine, which stiffens the chassis considerably and reduces torsional flex for more-precise handling. BBR's handmade prototype was heat-treated after welding, as the production frames will be, and the result was a chassis that's 2 pounds lighter than the stock steel frame. Combined with the Marzocchi fork and Super Pro swingarm, the perimeter frame provides 8 inches of travel, front and rear, and handling is as crisp as any full-sized works bike.BBR reports that the KLX/DR-Z110 aluminum-perimeter frame kit will include the frame and long swingarm; an Elka shock; a billet brake pedal with bearings; an extruded-plastic gas tank (by IMS), with the same capacity as stock; an aluminum D-Section exhaust; and side plates. The company is also developing a hydraulic rear disc-brake kit for the 110, complete with billet rear hub. As usual, it will sell complete "shop" bikes in green, yellow or trademark black.We had several test riders sample BBR's DR-Z110 chassis, and all raved about the improved tracking over rough ground and excellent turning manners. This was partly due to the rigidity of the Marzocchi fork, but the aluminum chassis made the 110 handle more like an RM-Z250 than the DR-Z125. In fact, more than one pro rider wanted to ride BBR's DR-Z160 at Langtown, instead of its standard CRF175F, as the Suzuki motor was faster around the tight track.Motor EngineeringThus far, aftermarket companies have pushed the mighty 110 to 130. BBR has its own 130cc kit, which includes a 57mm piston, rings and gaskets, plus the cost of boring the stock cylinder. In conjunction with the performance cam, the kit improves power across the board, but the brothers Brown wanted much more. So Carmichael's DR-Z got a prototype 160cc big-bore kit, which will come complete with a 63.5mm piston and a billet cylinder and gaskets, and it will be tuned to work with the BBR cam, the aluminum D-Section exhaust and a 26mm carburetor kit. BBR also installed its four-speed transmission conversion on the prototype 160cc mill, and the result is a bike that rips! It has much more low-end torque and pulls through the midrange like a fully-modified Takegawa 124cc CRF50/70. Top-end is insane, and that is with the stock head and ignition. An internal-rotor ignition would make the engine faster still and would probably make it necessary to install a thicker, stronger connecting rod. The prototype we tested was jetted perfectly and ran like a miniature 250F, so we can't wait to get the production version for our Ricky Replica, on which the pieces will be tuned for even more meat.The prototype was fitted with the Pit Boss hydraulic clutch kit, giving riders greater control of the power. Still, this maximum mini would easily spin its Dunlop rubber on well-watered loam. Power is also managed by the RK Gold 420 chain and Renthal rear chain wheel. The IMS folding shifter and BBR aluminum skid plate protect your engine investment, too. BBR has yet to waste a wheel with the stock spokes, so OEM spokes are laced to the yellow-anodized aluminum BBR rims for strength and lightness.ConclusionAfter a full day of abusing Carmichael's works DR-Z160, we were impressed with the leaps and bounds BBR Motorsports has made with the diminutive KLX/DR-Z110. Doubling the suspension travel and quadrupling chassis rigidity make the pit bike handle like a works-grade big bike, and BBR's 160cc motor is the easiest-starting, smoothest-running one we've experienced thus far-and it's not even finished yet! If Carmichael's Team Suzuki RM-Z450 has the same performance advantage over stock that BBR's 160 has over the DR-Z110, we'd hate to be Reed or Stewart when the gate drops on the outdoor season.