Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/126938
The 1987 Suzuki RM 125H is an entirely new motorcycle compared to last year's G-model. It has strong low-end and mid-range power, but a Expert-level rider will want a bit more on top. Test: 1.987 Suzuki RM1.25H Still yellow but no longer mellow By Kit Palmer Looking back at the 1986 Suzuki RM125G, the first thing that comes to mind is horsepower or, should we say, the lack of horsepower. There was a bright side to the 8 RMI25G; it had one of the best suspension and handling pack- I ages around, but it was still overshadowed by its slow-rev- ving and plainly underpowered motor. Now we have me 1987 Suzuki RMl25H mat - besides basic coloring and styling - is truly an all new motorcycle. The new Suzuki didn't take on just some minor refinements, but features major changes in every department. Leading the way is a brand new piston-port, reed-valve motor with a totally redesigned powervalve, a new cartridge Kayaba fork, all-new Full Floater rear suspension linkages, a piggyback Kayaba shock, a beefed-up front disc brake and a removable rear frame section. Nearly everything on me new RM has been reworked or at least touched-up. Suzuki engineers focused on a number of shortcomings that plagued me 1986 RM125. Top priority was the water-cooled, I 23cc, two-stroke motor and it received most of the attention starting wim the Automatic Exhaust Control Timing (AETC) power-valve. Last year's power-valve varied exhaust flow volume at different rpm ranges. The new AETC system uses two guillotine-type valves in the exhaust chamber to alter exhaust timing. The valves stay closed at low and middle rpm and then gradually open as the revs rise. The new power-valve still has a spring-loaded adjustment knob externally-mounted on ·the AETC that changes how soon or late me powervalve opens and closes to compensate for different track conditions. At the opposite side of the cylinder is a new piston-port, full-reed valve intake chamber mat replaces the old style case-reed valve induction system. Suzuki claims having the piston port full-reed valve design produces a higher velocity of fuel/air mixture into the cylinder to improve engine response. The new Suzuki's crank is 3mm smaller in diameter - designed to decrease volume in the lower end to make the motor more responsive. Carried over from last year's RMI25 is a flat-top piston, but the 1987 model has one ring instead of two. To lower weight and dissipate heat better, me RM-H has a boron composite cylinder that replaces the standard iron cylinder liner. Since the new RM is designed to rev quicker and higher than before, me motor requires a larger volume of air/fuel mixture to keep from starving. So the RM-H has an all-new airbox that is noticeably larger than me RM-G. The airbox and fil ter element are bigger as is the airboat that connects the airbox to the carburetor. Carburetioh is handled by a 34mm flat-slide Mikuni with new jetting specs and a redesigned floatbowl that eliminates bogging when landing orr big jumps. During sharp jolts when riding the RM-G, air bubbles would form in the floatbowl and get sucked up into the mainjet, causing a bog or hesitation when the throttle was twisted open. Other motor changes include a new electronically-timed magneto and an external rOlDr ignition, a new exhaust pipe, different gear ratios in the six-speed constant mesh transmission, and a new more reliable and more efficient water pump drive system. In additon, the suspension and chassis on the new Suzuki are radically changed over last year's model. Although the RM-G had first-rate suspension, Suzuki felt it could still be improved upon. Suzuki's main goal wa to make the rear Full Floater and front suspension work more freely .and smoothly than before. After only one year in production, Suzuki dropped the eccentric cam concept in the rear Full Floater suspension for a less friction' 'beLl-erartk" linkage design. According to Suzuki, the eccentric cam system didn't work freely enough throughout the wheel stroke, which also made it difficult to accurately fine tune the rear suspension. What Suzuki came up with is closer to a "conventional" linkage design that has a more progressive ratio and employs needle bearings at all pivot points and low-friction unibell spherical bearings at both ends of me shock. The single Kayaba shock is also all new. For starters, it now has a piggyback reservoir, instead of a remote reservoir, designed primarily for reliability purposes and better cooling. The shock itself has all-new valving and has 21-way external compression and rebound damping adjustment settings. To help m.ake the shock perform as friction-free as possible, me