Cycle News - Archive Issues - 1980's

(Left) Radiator is low on the frame for good weight distribution. but could be vulnerable. (Rightl New hub and straight pull spokes. By Terry Whytal Suzuki's newest ankle-bher, the RM125X, is a well designed, innovative piece of equipment. And, most importantly, it works almost flawbike is running that mud will not build I essI y. up in the mesh. Recent years had seen a de· cline in the popularity of the RM . r d b line o~ mot~crossers ofrere y SuzukI. Their once capable design features had been refined as far as possible and the marque needed a new approach. Enter the Full-Floater suspension and exit the critics. The new singleshock, rising-rate suspension found instant success on the works bikes and quickly Suzuki incorporated them in the '81 RM lineup. After many lengthy delays, (which allowed its competitors to grab much of the market), Suzuki released the RM125X to the public. Trophies and plaudits soon rained down on the smallest Floater and we waited impatiently for our test bike to arrive. Finally, with the bike tucked safely in our van, we headed for the track. Looking over the RM carefully before taking the first laps gave us a chance to note the many changes from last year's model. Most obvious of the new features is the radiator mounted on the front downtube. Suzuki first used watercooling on the 125cc works bikes raced in Europe three years ago. The system proved effective and last year's factory machines ridden hy Mark Barnett and Brian Myerscough carried liquid-cooled engines to several victories and the National 125cc MX Championship. The '81 production RM uses nearly the same components as last yeaT's prototypes. Capacity of the system is slightly less than one quart, yet almost seven gallons are circulated per minute to assure cooling. The radiator's position on the frame is both good and bad. Mud and rocks could clog or damage the radiator's' fins because they are directly in line with debris thrown frpm the front wheel. Suzuki has covered the radiator with a very substantial screen designed to deflect rocks and vibrate enough when the We never had a problem with. the unit, although true muddy conditions were never encountered. On the other hand, the low placing of the radiator helps keep the center of gravity in line with the bike's axis, and the hoses con· necting the pump and head to the radiator are short and well protected. Clearance between the cylinder walls and the piston and rings are much tighter than in air-cooled engines and require a five minute warm·up time before riding to help preyent cold seizure problems. One stab at the kick lever was all that was usually needed to fITe the little RM. After warm-up, the bike runs crisply even low in the powerband. . Acceleration is on par with the Honda and Yamaha water-pumpers and just as importantly, the power spread is very forgiving. As with most 125cc hyper-bikes the rider must use the gearbox capably but the test riders all agreed the 'Zook could be ridden a gear higher through many turns. Leaving one finger on the clutch lever was standard riding procedcure. Following the example of Mark Bar· nett's National winning style, we would approach a berm at near right angles, pitch the machine sideways at the last possible moment while holding the throttle full on and just touching the clutch. Exit from the turn would then be smooth and fast. Much of the credit for the Suzuki's strong drive from often choppy, corners goes to the Full·F1oater rear suspension. The shock is mounted to the base of the swingarm and rising rate linkage ca.-Qes the wheel forces to the top of the unit. ibis - "floating" concept differs from mO,st single shock designs, which have their shocks mounted to the frame. Test riders quickly voted the suspen· sion as better than any production bike yet ridden. Its 12.3 inches of trav~1 made rough sections a pleasure to nde throul{h. In one outmg, the little 125cc mount was able to pull away from several 250cc bikes in acceleration tests across medium sized whoops. Landing from big jumps provided the rider with a good feel for the benefits of a rising rate suspension, easing the bike back to the ground instead of slamming down. The only time we were able to bottom the rear suspension was off a double jump at Carlsbad raceway because the bike was unable to clear the distance cleanly and the rear wheel would hit the side of the second jump. We have encountered no cases of wheel breakage on the '81 RMs, thanks to an all new hub design with straight-pull spokes. Wheels forces are more evenly distributed across the new hubs and the weak point of the spoke, its sharp bend, is eliminated. The brakes housed within the hubs are typically Suzuki, which means they work well if not spectacularly. The X model Suzuki's only handling flaw comes to light when braking on downhills. As weight transfers to the front suspension, the bike exhibits a tendency to wag its head. The problem was never serious and if the rider made sure to keep his weight back over the seat, the 11.2-inch travel KYB forks were able to handle their end. Suzuki claims a dry weight of 194 pounds which seems about right. flicking the RM from side to side when airborne is effortless and controlled. In fact you could almost summa~e ~e bike with the word effortless. Plckmg lines to pass a slower rider becomes easier as the suspension soaks up terrain that might swallow lesser bikes, and the engine's good mid-range torque will pull the rider from some tough spots. Certain details of the Suzuki s~m unusual. The number plates are held on with straight slot screws and the throttle cable still exits the throttle housing at right angles, leaving the cable in a snag prone location. On the plus side, the chain adjusters are. contained inside the box sectlon alummum swingarm and :work perfectly while the airbox and sldepanels have speCIal guides that flow air to the filters and keep water and dirt out. As a package, the '81 RMX is the most complete 125cc bike offered. to the public this year. It should requITe less modification for the Pro class than any other mount and lesser riders should be content with the stock rna· chine. Even the rear shock, long the bain of Japanese manufacturers, is not likely to be bettered on the aftermarket. The unit is light, offers easy pre-load and damping adjustment and just plain works. The rider is still the most important ingredient in racing and all of the current crop of 125cc MXers are capable of winning. Suzuki riders will have an advantage over their compe,titors, however. They'll be the ones having the most fun. • Specifications Engine .•..........'. . . .. Two-stroke'single. power reed. liquid cooled Displacement ........•...........•......................... 123cc ·C8rb ..........................••...•....•.......... 32mm Mikuni Bore and stroke ....•............................... 54mm x 54mm Transmission Six speed constent mesh Front suspension Leading axle. air assisted. 11.2 in. travel Rear suspension ....•.. Single shock. rising rate linkage. 12.3 in. travel Swingarm Aluminum. box section Ground clearance.......................................•.. 13.6 in. TIres , IRC. 3.00x21 front. 4.10x18 raar Fuel tenk capecity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7 gal. Wheelbase...............••..•.........................•.. 56.7 in. Weight..•...•........•..............•..........•...•..... 1941bs. Suggested rateil .....•....•.......•............•........•...•1579 35

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