Suzuki Rm250

SUZUKI RM250

Are Minor Updates Enough to Keep the RM250 King?

CYCLE WORLD TEST

Suzuki caught the other motocross manufacturers napping when they introduced the first Full-Floaters three model years ago. No other brand’s rear suspension came close to match ing the sheer smoothness and comfort of the Full-Floater. Adding insult to injury, an RM of any given size felt at least one size smaller than it actually was: the 125 was as agile and quick handling as a 100; the 250 RM was like a 125; and the 465 could be flicked around much like a 250. When CW’s 1981 Best Bike Awards rolled around we picked the 125, 250

Revised porting and ignition timing moves the powerband down the rpm scale.Short-shift. the RM and no Other stock 250 can beat it.

. New 4$mmKVB . J~iJts stilt have 11.2 Iñ~ of travel, b~utarp stronger and use coñ~ tinuously a~justabIe coq?pres~iO)1 damping. The RM still feels light and responsive, only now steering response `is letter.

and 465RMs as the best motocrossers of the year. No brand ever won all three CW classes in a single year before. The 125 and 250 again won the CW Best Award last year.

Meanwhile the other manufacturers were burning the midnight oil. Most of these new designs became available this year. The ’83 RMs were introduced to the press mostly unchanged, with the exception of blue seat covers and minor mechanical honing. We questioned the lack of innovation. How could the '83s stay competitive with so little change? Still, they were so good before. Maybe it would be enough.

The ’83 RM250 was the most changed and the one we requested first.

The most obvious change to the new RM250 is the front end. New KYB forks with 43mm stanchions are used. Wheel travel remains 1 1.2 inches, from half to a full inch less travel than most of the other motocross 250s. The tops of the stanchion tubes have air caps in case you want to add air although most riders will be happy without. Inside the bright yellow lower sliders are new damper rods. A slot-head screw under a rubber cover on the bottom of each slider adjusts compression damping. The adjustments are different from any we’ve seen before; the screw is turned one complete turn and counted as, you guessed it, one. There’s no click or detent, so it’s wise to turn the screw clockwise until it lightly bottoms before adjustment starts. All the way in is the stiffest damping, eight full turns out is the softest. The screw will turn more than eight turns but everything after that number remains the same as eight. The adjusters are set stock at number four. We found that setting much too stiff. Choice varied among riders but most liked the adjustment at eight, the softest setting. As fork oil gets thinner with use and parts get more clearance, it will probably become necessary to adjust to a stiffer number. It’s also nice to be able to change the fork’s action for different tracks.

At the rear, aluminum struts between the swing arm and rocker add a refined touch. The struts aren't adjustable and maybe it’s just as well. Not many riders would bother anyway. Rear wheel travel is 12.7 in. The aluminum-bodied shock has a knob at the top to adjust rebound damping to one of four click positions. Standard is position two. Turning the plastic wheel adjuster requires removal of the side cover but we didn’t find anyone who wanted to change it anyway. Still it should be located in a more easily reached spot. Compression damping is also adjustable. Four click positions are furnished with number two being the standard setting. Changing the position requires a flat-blade screwdriver. The adjuster is on the bottom of the aluminum-bodied reservoir where it’s a little awkward to see but not as tough as the fork’s adjustment screw.

The rest of the Floater rear is unchanged. The top rocker is made of welded-up aluminum stampings. It pivots on roller bearings and is supported by a shaft that runs all the way across the frame. The lower shock mounts to a bracket welded to the lower front of the extruded-aluminum swing arm. These parts are good looking and have proved durable the past couple of years—no need to change a good thing.

Anyway, back to the new stuff: the RM250 gets a double-leading shoe front brake for ’83. Suzuki was nearly the last to stay with the single leading shoe, for good reason; the front brake last year had good progression and strength. Few riders actually needed or wanted more front brake. You get it anyway this year. But don’t fear, the new brake retains that same controlled progression but more of it! It’s a nice clean design that uses aluminum control arms with the connecting link placed behind the axle.

A bunch of smaller things have changed: the shift lever is a forged aluminum part with a folding steel tip; the steel rear brake pedal has a folding claw tip, Bridgestone’s excellent M32 and M33 tires are standard, control cables are better quality and the decals are new.

The engine appears unchanged, and basically is, except for the porting and ignition. Both are modified to give better low and mid-range performance. Bore and stroke remain unchanged at 70 x 64mm. A flat-slide 38mm Mikuni feeds gas through an 8-petal reed valve. The cylinder is more port area than steel liner and a water jacket surrounds most of it. The clutch, transmission gears, primary gears, bearings and cases are the same. Ditto the pipe and steel silencer.

The strong chrome-moly steel frame is unchanged. Same for the wheel rims, hubs, chain guide, removable kick stand, hand levers, plastic components, radiators, footpegs, sprockets, spokes, throttle, and gas tank. The double-filter airbox is also the same but many will argue its merits. We’ve seen these boxes drilled full of holes, covers cut off, and the complete unit replaced with aftermarket filter boxes. The general belief is they don’t pass enough air. Wrong. The thick, double foam air filters do restrict air flow some but the problem is easily cured by simply replacing the stock filters with K&N filters. Flowbench testing proves the K&N filters allow more airflow with the unmodified filter covers in place than stock filters with the covers removed! Don’t throw the filter box away and don’t drill the covers full of holes. You’ll only let in water without significantly improving airflow. True, factory Suzuki racers use a different airbox, one that contains a single large filter, but the frames are also different. Take our word for it, put K&N filters in the stock box if more top end power is wanted. It works.

Riding the new RM250 immediately erases any doubt about the lack of major changes affecting the RM’s competitiveness. The ’83 is pure fun. It has the wonderful light, small feel that made the last two models so popular. The new torque porting is noticed as soon as you shift to second the bike starts wheelying. Same for the shift from second to third and from third to fourth if the rider keeps the throttle twisted. Neat. Top-end power isn't as strong as last year. The power band has a noticable flattening as the revs climb. The bike still pulls in top but not as strongly as last year’s bike. Thus, long, uphill starting areas like Saddleback Park’s will find the ’83 RM250 racer mid-pack instead of out front unless he short shifts.

If the RM is short shifted no other stock 250 will beat it to the first turn: over-rev the engine and you'll be midpack. The engine will wind but little power is made way up there. Most of the power is produced in the mid-range. The new powerband is better for most racers as they won’t have to keep the revs high to go fast. Also the new porting moves the big rush of power (as it comes on the pipe) to lower revs where most can easily control it.

Gear ratios are unchanged but work even better with the torque engine. Shifted from any gear into a higher gear, even uphill in sand, the engine never hesitates or wastes time getting on the pipe. The rear tire throws a roost of dirt more like an open bike. Carburetor jetting is perfect for our area. We didn’t have to change anything. The RM ran strong and crisp at all elevations.

Starting isn’t as good as it could be. The bike requires several brisk kicks when cold and two to three when warm, until the rider learns to crack the throttle about a quarter turn. The problem lies in the carb.; it doesn’t have a low-speed adjuster stop screw you know, the one that holds the slide to a certain height. Suzuki hasn't used them on the RMs for some time and we think it’s a mistake. The bikes start much easier with one. And the engine wouldn't try to stall with the throttle completely off and the brake applied hard. Experienced racers and trail riders aren't bothered much but novices complain until they adapt. Taking all of the slop out of the throttle cable and maybe just a tad more than all of it will help until the cable stretches and the carb slide drops lower again.

With the basic RM frame geometry and design in its third year of development, most aspects of the bike’s handling are nearly perfect. The RM «ever jumps sideways, never kicks or scares the rider. It just absorbs the nastiest terrain without complaint or terrifying side effects. Sliding forward for tight corners is easy. The lack of a safety seat doesn’t make any difference; the dipped top on the tank lets the rider slide right up on the top of it, if need be. When he’s that far forward, the rider’s right knee touches the pipe slightly but you’re not there long enough to matter. That aside, rider movement isn’t hampered by anything. The narrow center section, thanks to the single shock design, makes fore and aft movement quick and effortless.

All the RM’s pieces are quality and they're shaped so a broad range of rider sizes and shapes fit well. The bars, footpegs, shift lever, rear brake pedal, and hand levers are right for most riders.

Steering precision is perfect, thanks to the large-leg KYB forks. The bike can split hairs in corners. Changing lines if a rider falls in front of you is no problem, just steer around him. Jumps and gullys are great fun on the RM250. The bike handles just right. The light weight, neutral handling and lack of kick, means you can be fearless overjumps. Landings are simply absorbed without a whimper. And no shock is transmitted to the rider.

The front end of the RM doesn’t stick as well in corners as, say, a Maico or ’83 Honda. Unless the rider shifts his weight well forward, the front tire will skate a little on hard off-camber turns. If the rider moves around on the bike it’s no problem. The stock Bridgestone M32 and M33 tires are excellent. No need to change them until they’re worn out. They work well on a variety of surfaces.

Use a lot of caution when first pulling the new front brake. The action is a little more sudden than some of the other brands. Two fingers on the lever may be too much for some riders; start by using one finger until you’re acquainted. The rear brake is excellent and most riders find little to complain about. It stops quickly and doesn’t chatter.

Of course nothing is perfect, including the new RM250. The return spring for the folding tip rear brake pedal broke. And the headpipe springs aren't strong enough. After a few hours, the headpipe jumps in and out as the engine is blipped, clattering and making other terrible noises. Doubling the springs fixes the headpipe problem. No one liked the front fender for muddy conditions either. It doesn't have enough width or cross-curvature. Throw it away and put on a Gold Belt DeFender so you can see where you're going.

Back to the question we asked at the beginning of this test: Is the ’83 Suzuki RM250 going to stay the best 250 motocrosser? We haven't tested all the '83 motocrossers yet, but we did race against many of them during our test period. So, we’ll have to side-step the decision until we've done complete tests on the competitors bikes. Some of the other brands are nipping at the RM’s heels, but don’t be too surprised if you see the RM250 in the Ten Best Awards issue again this year.

SUZUKI

RM250

$2219