Cycle News - Archive Issues - 1970's

and they are thoughtfully protected by vented rubber boots over the sliders to prolong both fork and seal life. The front axle has been offset to gain the extra travel and it's worth it. The rea r suspension consists of remote reservoir nitrogen -flu id Kayaba dampers with dual rate springs which bolt up to a new design reinforced swingarm. The remote reservoir design, also proven on the GP bikes , is intended to prolong the optimum damping action of the shocks and it works . Measured rear wheel travel is 8 .8 inches. The-shocks themselves are slightly longer and mounted further forward on the ~ingann at a somewhat reduced angle compared to the "A" model. This slightly decreases the mechanical advantage in a compressed situation .and, theoretically, should result in a smoother ride and more rear wheelground contact. There are other detail refinements like the overdue chain tensioner built on to the swingann and a conical front brake hub which retains the same , swept braking area as the older full width hub . The air forks , remote reservoir shocks and other goodies bring the weight up to 194 pounds which is the same trend seen in the GP bikes as they go for more suspension travel. You have to pay the price somewhere, and . the four pounds of added weight will be unnoticed in racing. The longer travel suspension also results in nearly 12 inches of ground clearance, which means your feet are further above the bumps when the suspension is completely compressed. A very -full day of riding and racing followed the RM125B 's introduction. The question to be addressed was: Is it more better? The answer was surprising: Usually, but not always . " The standard suspension setting calls for 20 pounds per square inch (psi) in the front air fork along with the 87/182 inch-pounds (Ib/in) split springs that are delivered on the Kayaba dampers. It would appear to be designed for a rider in the 135-150 pound range. Both CN testers are a solid (well , pretty solid) 175 and found 'a ll that wheel travel to be deliv ered too softly for control and confidence in cornering. The fork air pressure was raised about six psi and we liked the front end's behavior a whole lot better. It didn't affect the second half of the fork 's travel but made the first four inches feel just about perfect. The relatively light 10 Iblin fork springs are an excellent choice for the combination system .. Fork function was quite good and with the adjustment possible to suit each rider there should be no complaints. It didn't twitch landing from jumps and the front end generally steered very well. Some tires are going to work better on the new RM than the stock IRC rubber (3.00 X 21 front , 4.10 X 18 rear) . In fact, tires are the only substantial change we would make on , the machine.: Lighter racers wili proba bly opt for lighter springs around the Kayabas. Heavyweights (and there are relatively few competing in the 125 class) may want more springing. The reservoirs perform their function. The increased oil capacity of the shock and the chance for som e circulation of the fluid combined to keep the dampers damping for as long as anybody could ride. The engine and gearbox a r e increasingly full-race oriented. Which also means th e new RMI25 is more difficult to ride than th e "A " version in any but full race conditions. They said the engine design was to give more mid-range torque but it wasn 't all that obvious. It would be interesting to see a reliable dyno FJlr:v.e on the motor .•It , ) didn't feel like it wanted to pull until around 7500 rpm. Past the torque peak at 9500, power to the ground drops off quickly and noticeably. The bottom line reads out to lots of gear shifting. The powerband was not as broad in application as was the " A " model or even compared to other 125s that may, ultimately , be as fast. The "B" model is, however, fast. In fact , it will probably give a better account of itself on a course approaching true Grand Prix dimensions than on the more common short courses. The requirement to use the gearbox a lot to get the desired performance out of the "B" pointed out the fact that the gearbox on our test bike was not all that trick. It would not shift sharply when under load and generally felt very tight. Even expert riders were blowing shifts and had to use the clutch to execute shifts when accelerating. This becomes a drag since you have to grab a lot ' of gears coming out of a corner to match the very close gearbox ratios to the very rapid rpm climb. Throttle response often outran many riders' abilities to manipulate the gearbox to match . There are two considerations here. One is that you may need to become a fairly expert rider to realize the potential of the RM125B (which is probably true in any case). The second is that the gearbox may loosen up with use, allowing clutchless first time shifts. Both are very likely to apply. The only change in frame geometry is one millimeter less trail and half an inch more wheelbase. Those small changes should allow the "B" to turn a little' better and be more stable in straight line charges. After a few hours exposure , the opinions were mixed. Some felt just the opposite applied, i.e. , it was less stable than the " A" model both in turns and down the straights '- possibly because the rear end kicked around a little when it wasn 't under compression. More time is needed on the bike (like weeks) to figure out exactly what the effects of change have been on the performance. Front and rear weight distribution was very good. You can correct the RM 's position in mid-air with ease and straighten it out on touchdown with either body weight or throttle, or both. Like most long travel suspension motocrossers, the Suzuki wants to ride up on a berm, You have to hold it down purposefully to keep it cranked over and execute the turn. High sides will result if you don't work at it. The brakes were excellent , particularly the front brake. It was very powerful yet very progressive and sure in motion. The rear brake was not grabby even though Jess progressive in feel than the front . It was certainly strong enough for a 125 bike and rider but did induce some rear wheel hop under especially hard braking. As usual for motocross, the RM "B" encourages a rider to use the front brake a lot with the rear just enough for stability or when necessary for serious stopping - like the unbenned 90 degree turn at the end of a straight. The bike-rider physical relationship drew no complaints. Controls are wellplaced, footpeg : height and position felt comfortable even for six-footers, and the seat-tank relationship is one of the better designs we've ever encountered. The seat was initially a little hard but that foam should break in ' nicel y after a few weeks' riding. The Takasgo rims are laced to hubs in a cross-three pattern with what we judged to be nin e-gauge spokes . They must be good wheels since tester Gary "Skysho t" Hymes didn't break them, and he has been known to break cast alloy wheels in an hour's outing. The handlebars are wide at 34.5 inches but a hacksaw can tailor them to fit whoever owns the bike, :The. bend and " 1 RM IZSB SHOC IC ABSORBER RM /2S8 POW£III1F:£D DETA/1.. RMleSB II/II FORKS ) shape are quite satisfactory - as they have been on past RMs. The 'bars are still made of chrome- moly steel painted black, just like the frame . The recommended retail price for the whole package is $1025. The price jump doesn't even begin to account for the added expense of remote reservoir shocks (which were about $150 when you could get them) and the all -new air -spring front fork. It's still a bargain . As is true of all racing 125s we're familiar with, there is a noticeable power drop when the engine has been running for a long time and gotten nice and hot. The one or two horsepower power loss which would go unnoticed on a 500 class bike ends up making a difference in the response of a 125. This heat buildup power loss is not a specific criticism of th e Suzuki, but the gen eral rule does apply to it. And th ere is still the question of tying th e useable pow erband to th e RM125B 's handling char ac teristics. It's premature to draw a ny finn conclusions at this point on whether that sid e of its personality really is an im p rovement over the " A " model. ' O ne thing we do feel to be true of the -_."B " model --Suzuki -- that the is gnarlier and nastier the course is, the better this RM125 will shine. It eats up whoop-dee -doos and bumps that should be bone-jarring. You tense for the impact that never comes. If the tight gearbox loosens up with use, the RMI25B will probably be the bike in its class when it comes to tackling tough circuits. It is heavily influenced by the Suzuki World Championship Grand Prix bikes. The closer you and the bike - get to Grand Prix racing conditions, the better you and the bike - will perform. • Specifications Engine . . . . . . . Two-stroke piston and reed port, air-cooled Bore X stroke 54mm X 54mm Displacement 123.67cc Carburetion . . Mikuni 32mm VM32SS Wheelbase 55.3 inches + 1- half an inch Front suspension . .. Ka yaba air-spring fork with 9.1 inches travel Rear suspension Kayaba remote reservoir dampers with 87/182 split springs w/8.8 inches travel Weight(dry) 1941bs. Reco~men~,:~ retail price, ~ : : . ~ I 02~ _ ' 9 )

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