Cycle News - Archive Issues - 1980's

Bob Hannah joined Team Suzuki as a factory motocrosser and race-and-developement advisor last year, the company has taken a new lease on life. With Hannah's riding talent and experience now a part of the Suzuki team, the company's aim is to get back into some serious motocross racing in 1987. This enthusiastic attitude, says Suzuki, is re£lected in the design of the 1987 production Suzuki RM250. Hannah's mission: To develop a competitive 250cc motocrosser for 1987, using the not-so-hot 1986 Suzuki RM250 as a scarring point. The results of Hannah's research and developemenc can be seen in the new 1987 Suzuki RM250H. Just about every inch of the RM has been reworked, replaced or r~designed. A lot of attention has been focused on the RM's suspension. Last year's fork came set up way too soft, while the rear Full Floa ter suspension system was overly stiff and harsh. Suzuki replaced last year's conventional fork with an all-new cartridge damper system. The new Kayaba-made fork features a cartridge design similar to the unit used on last year's production Honda CRs. The cartridge is designed to prevent air from mixing with the fork oil to provide smoother, more positive action. The new fork also has 20-way compression and rebound damping adj ustments. The rear Full-Floating suspension is all new. Ct'ne for '87 is the eccentric cam design. It has been replaced by a more conventional linkage system. Suzuki_ felt the eccentric cam design didn't operate freely enough, cau ing a harsh ride and making it difficult to finely tune the single Kayaba shock._ With the new bell-crank linkage design, Suzuki was able to come up with a more progressive stroke ratio, that also employs needle bearings at all pivot points and low-friction unibell spherical bearings at both ends of the hock. The shock itself is all new, too, as is the swingarm. The Kayaba shock now features a piggyback reservoir, replacing the less effective and less reliable remote reservoir. The new reservoir is larger and holds more oil to improve cooling and dampin$ action. And to help reduce friction III the stroke, the inner shock body is treated with an Alamite coating. With the new linkages and ratio changes, the hock's valving also is all new. There are 21 external compression and rebound damping adjustments. The blue-painted chromemolybdenum steel tubing frame has slightly altered geometry to achieve a more level riding position, getting away from last year's high-in-theback, low-in-the-front feeling. It also features a removable rear frame section on the left side only. This means the exhaust pipe and silencer don't have to be split in order to remove the rear frame section when servicing the rear suspension. Oliler cll",si, ch"n~l's includl' ;dlnew front and rear brakes. Many Suzuki owners complained about a mushy (not to mention weak) front disc brake on last year's RM, so the 1987 comes stock with a hard pia tic brake hose, which replaces last year's rubber hose. Although most MX bikes from Japan have steel-braided hoses, Suzuki feels the hard plastic hose is the way to go, saying it's just as effective but less costly to manufacture than the steel-braided hose. The disc brake caliper has a doublepiston design. Unlike the 1987 RM125, the 250 comes stock with a rear disc brake. The caliper is' moun.ted above the The clutch has a much lighter pull and smooth engagement. The new disc brake is powerfull and has excellent feel. A piggyback reservoir replaces last year's remote design. low-end is the motor's strongpoint; powerband is usable. The new RM has the motor to get from one turn to another extremely quick; has the suspension to keep up and the brakes to slow it all down. , swingarm; is activated through a rubber brake hose and has two piston. The disc is 8.7 inches in diameter. Tucked insidi· thl' all-new chassis is a reworked, water-cooled, twostroke motor. Both the RMl25 and 250 hare the same type power-valve concept this year. The Automatic Exhaust Control System (AECS) on the 250 conrains two sliding exhaust valves located in the upper part of the exhaust port. These guillotinetype valves alter exhaust timing. The valves stay closed at low and middle rpm and graduallly open a revs increase. Like last year's power-valve, a spring-loaded adjustment knob is externally-mounted on the AECS. It allows riders to change how soon or late the power-valve opens and closes to compensate for different track condi tions. The cylinder received minor port timing changes, and the whole unit weighs lighter than before because of a new sleeve. A new Suzuki Boron Composite-plated (SB'C) sleeve replaces last year's iron-made component. Not only is the new sleeve lighter, but the SBC keeps the motor running cooler by means of better heat.dissipation. Feeding the combustion chaqlber through a piston-port reed-valve is a 38mm £lat-slide Mikuni carburetor that's been reworked for cleaner throttle response. Last year's carb The cartridge-design Kayaba fork has first-rate performance. had a design £law in the float bowl area, causing the motor to bog when landing off jumps. The gas in the float bowl would foam up and bubbles would find their way into the pilot jet, causing the engine to bog when the' throttle was first applied. The area around the float bowl is redesigned to eliminate this problem. Attached to the carburetor is a larger airbox and airbox-tocarburetor boot, which greatly improves air flow to the carbo Last year's set up was way too restrictive. On the track Just about everything we didn't like about last year's Suzuki has been improved for 1987, in one way or another. The most noticable improvement. is the suspension. The RM has gone fTom the -worst suspension package in 1986 to one of the best In 1987. After making basic adj ustments, the spring preload and the compression and rebound damping settings on both the fork and hock, the Suzuki feels goodjammingover whoops and bumps. Much of this has to do with the new cartridge Kayaba fork. it soaks up the bumps without pounding your arms to death like last year's fork did. Fork action is super smooth and progressive, and heads hake is almo t non-existent. Bottoming the fork wasn't uncommon; that was clearly evident by black tire marks found underneath the front fender on our Suzuki. In the rear, the new Kayaba shock works as well as the fork, allowing the front and rear suspension systems to work in harmony, unlike last year's RM. The rear shock has mooth stroke action and almost no tiction. This, combined with new valving and linkage ratios, gives the RM excellent feel over the bumps. The back end tracks' well when powering down a rough straightaway and rarely does ·any swapping or anything unexpected. The overall package is very predictable and stable on the track. Even when traveling over nasty stutter bumps and while hard on the brakes the Suzuki is easy to control - the front end doesn't twitch and shake all that much, and the rear tire stays close to the ground. Both front and rear brakes are much improved on the new Suzuki. The rear disc is powerful yet doesn't havl' the teneknc)' to lock up. Thl' front disc is stron~ and has a mllch 11 bellt'!" fl'l'1. The nt'w hard-plastic

• Cover