Kawasaki Kdx250
KAWASAKI KDX250
Open Bike Torque Small Bike Agility.
CYCLE WORLD TEST
Last time we tested a Kawasaki KDX250 (Aug. ’80) the bike was part of a seven-bike enduro comparison. Although it was the first to arrive at our office, it was the last to be ridden. It was flat homely and all the testers were sure it would be the least desirable. Initial break-in miles started changing the testers’ opinions and after six hard days of riding including mountains, desert, foothills, creeks, sandwashes, uphills, downhills, sound tests, top speed runs, drag races, timed wheel changes and ease of normal maintenance, the ugly green bike came out the overall winner.
Last year the KDX lost most of its ugly styling and got a Uni-Trak rear suspension. For ’82 it has been further improved. Maybe improved isn’t the right description; the ’82 KDX has little in common with the great but unsightly ’80. The wheel hubs are the only parts carried over. Everything else is new.
The 1980 KDX had a very impressive reed valve engine with a correctly-spaced five-speed transmission. The ’82 still has a reed valve engine but it’s all-new and has a six-speed transmission.
The new engine is a brother to the unit in the KX motorcrosser tested last month. Small tidy cases, Electo-Fusion cylinder bore, modern porting, eightpetal fiber reeds, strong clutch, positive shifting mechanism, primary kick starting, full-circle flywheel weights, outside flywheel CDI ignition, rear-set countershaft sprocket and light weight are some of its features.
Differences between the enduro and motorcross engine start with the sixspeed; the KX has a five-speed. Bore and stroke are the same, but compression is slightly higher on the MX, 8.4:1 compared with 8.2:1. Although the cylinder porting looks identical, it also is different. Intake and transfer port timing is the same; the exhaust port on the enduro is lower for better torque and low-end power. Ignitions also differ; the enduro is equipped with a small lighting coil to run the lights and the timing advance is 17° compared with 14° for the MXer. Normal practice is just the opposite on most makes; the MX models usually have the most advanced timing. The KX also has a larger carb than the KDX, 38 mm compared with 36mm. Pipes on the motocross and enduro models are identical until the stinger. The enduro stinger is Vs in. larger in diameter and is followed by a huge silencer that’s 11 in. longer.
A new chrome-moly frame surrounds the new engine. It’s strong, has good triangulation in its mid-section and around the steering head. It also is a spin-off from the motocrosser frame. It has the same size tubes and general configuration with modifications and additions for enduro use. The steering head angle is pulled in one degree steeper than that of the motocrosser, 30° on the MX, 29° on the enduro. The wishbone area below the motor has some additional tubes and bolted-on tubes wrap around the engine’s side cases, eliminating the need for a mud-collecting skid plate. Extended seat rails serve as a rear fender loop tool bag attachment and grab handle, and are nicely braced by two additional tubes.
The Uni-Trak rocker and struts are the same as the parts used on the motocrosser. They’re strong components, the rocker made from stamped steel parts welded together, the struts from steel tubes. Lengths of these parts are different from those of years past and the new arrangement gives a progressive rather than linear action. This means the shock can react easier to small bumps without bottoming on large ones. Bearings are a combination of spherical, bushings, and caged rollers. The huge aluminum swing arm from the KX is modified for enduro use. It sports extruded aluminum arms with plenty of cross-bracing, open-slot rear axle mounting, snail adjusters, a welded-on kick stand bracket and massive gusseting under the strut area, all good stuff that won’t need replacement for a long time.
Suspension travel is 10.2 in. front, 10.6 in. rear. It’s more than needed in mountainous terrain, just about enough for open desert. A good compromise. The rear shock doesn’t offer the adjustable rebound damping found on the MX and the remote reservoir isn’t finned. We didn’t find a need for either one. A single, straight-wound spring is used and it can be adjusted for preload, although it’s difficult to reach. Kawasaki’s owner’s manual recommends removing the shock from the bike and holding it in a bench vise to adjust spring preload. As we do with other single shock bikes, we laid the bike on its side and used a long drift punch and big hammer.
Forks are KYB with 38mm stanchion tubes. They are held firmly in double-bolt triple clamps and the leg height can be adjusted up and down to fine tune steering quickness. Air caps are standard but hardly necessary. Other adjustments include oil weight and volume.
Plastic components on the KDX are first class. Fenders are long, wide and protect the rider. The taillight blends into the rear fender nicely and the lens doesn’t fall off. The headlight is adjustable for height and has a protective plastic lens cover so it doesn’t break when roosted by rocks from the rear wheel ahead of you. Although it’s only got 35 watts it throws a lot of light and the bike can be ridden at a brisk pace after sunset. The short gas tank holds 3.3 gal. of premix, enough for 80 to 100 mi. with a fast rider aboard. Standard enduro features include a rear fender mounted tool bag. The bag is
made of vinyl, has a plastic zipper and outside belt hold-down. It doesn’t have a protective tool tray bottom like some enduro bikes. The basic design is good but the material is questionable. Made of leather it would be great. The same odometer Kawasaki introduced a couple of years back is used. It has a resetable side and a total mileage side. Nice. If it had a flexible reset stalk it would be nearly perfect. A flexible reset stalk might prevent damage when the rider is trying to reset or adjust mileage while bouncing around on a whooped trail at speed. A flexible plastic guard is placed between the chain and the rear wheel, the better to keep tire-slung mud from piling up on the chain. And an excellent chain guide is standard. It has a long-lasting rub block bottom and sides that allow fore and aft adjustment so it can always be as close as possible to the sprocket.
Controls are a mix of good, fair and soso. Hand levers are okay and have protective rubber mud guards. Grips are fine. The brake pedal has a claw top and the brake rod end is positioned over the swing arm pivot where it should be. The shift lever and throttle are the so-so we mentioned. The shift lever winds around, as Kawasaki levers quite often do. Problem is it doesn't have a folding tip. To help avoid transmission damage from smashing into tree roots and rocks, the engineers have tucked it in quite well. That means the rider has to ride with his left foot turned in to shift or his foot will miss the lever tip. A folding lever would be simpler and the rider could ride with his foot in a normal position. The throttle appears good. And it does turn easy and return promptly. But, it’s made of too many parts and it’s fragile. There is a steel plate positioned between the grip and throttle body that’s easily bent. Our first crash deformed the part and required some trail-side reforming with a rock and screwdriver before we could continue. The throttle cable exits parallel the bars as it should, but it doesn’t need nearly as many pieces, especially stamped steel ones.
Wheel rims, spokes, and tires are fine for most conditions. The Bridgestone M22 and M23 tires are better on wet or damp ground than dry, but aren’t too bad anywhere. Rims are aluminum and strong. Spokes don’t look exceptionally large but they didn't break or work loose.
The KDX250 isn’t as easy to start as most 250s. It requires a faster than normal kick before the ignition makes a spark. It took us a while to get the message. Half-hearted kicks won’t start the KDX. Kick it fast, much like an open bike and it’ll start right up. Of course the kick lever bottoms on the footpeg and fast kicks soon become a little painful. It’s about time someone put a rubber cushion at the bottom of the kick start lever’s throw. Warm-up is delightfully quiet thanks to the 24-in. silencer. And a baby could pull the clutch lever without trying hard.
Stock the suspension is set up on the hard side at both ends. Our heavier enduro riders and average weight pro motocross riders thought it was perfect. Lighter weight enduro riders and less than pro motocrossers need it softer. Changing the fork oil to 5w and backing off the rear shock’s spring preload cured most complaints. We used the KDX in the mountains, desert and foothills. It worked very well every place. Jetting was unaffected by elevation changes, sea level to 8000 feet it ran fine.
An amazing amount of torque is in the little 250 engine. Climbing hills, even nearly vertical ones, is easy. In fact the KDX will climb almost any hill in 2nd! Sheer cliffs might require 1st. And we clocked the bike across a wet lake bed at 80mph, rider sitting up in the saddle. That means it’ll probably top 85 on hard ground. Best of all, the ratios match the engine’s torque perfectly. No flat spots or bogging occur before the bike gets on the pipe after shifting. It’s on the pipe all the time. Short shifting the KDX like a larger enduro bike works great. There is a noticable flattening of power at high revs, the result of tuning for low rpm torque.
Better have good brakes when you ride a dirt bike that will top 80 mph. The KDX250 does. The front brake is strong and progressive and doesn’t grab. The rear, larger than the one used on Kawasaki’s MX, also does a fine job. Stopping or quick slowing over whooped or bumpy ground doesn’t cause rear suspension lock-up or rear wheel chatter. No, the KDX doesn’t have a full-floating rear brake. The static arm on full-floaters lenghtens the time required to remove the rear wheel, no good on an enduro bike. The KDX backing plate attaches to the swing arm via a tongue and slot like an IT. But the front of the brake rod is positioned over the swing arm pivot bolt so the brake doesn’t change tension as the rear wheel moves up and down.
Steering precision is very good on the KDX. The lack of 43mm forks (it has 38mm units) isn’t a problem. With the limited fork travel they don’t flex enough to feel. Cornering is quick and easy and positive. Where you point it is where it goes.
KAWASAKI KDX25O
$1979
Complaints about the ’82 KDX are few; the stock foam air filter will need cleaning often due to its small size, and it requires the removal of four screws before it can be done, not the quickest job if you’ve just drowned the engine in a toodeep creek. And we’d like to see the tool bag made of real leather. Even so not many enduro bikes come with provisions for carrying tools. And the throttle should be more crash proof.
Still, the KDX is an amazing motorcycle. All our testers had a ball riding it, even those who prefer open machines. The incredible torque and ease of handling won them over. One tester, a guy who has never owned anything smaller than an open bike (he’s a 6-foot-2 desert expert) and never owned a Japanese bike, bought a new KDX250 after a 100 mi. ride through the Mojave Desert. He does look a little funny on it with orange and white leathers and helmet though!
