Kawasaki Kdx400
KAWASAKI KDX400
A Big Bore Enduro Bike Designed by Americans
When Kawasaki got back into the serious dirt bike business last year, the new machines were motocrossers, the KX125 and KX250. Not bad. either, so the enduro and play bike crowd naturally figured that
when the Green Machine did some enduro machines, they'd be based on the motocross models, just like tradition calls for.
Didn't happen. Kawasaki’s first serious true enduro bike is a 400. full name KDX400. It isn’t based on a motocross mount, instead it could be called an American motorcycle.
Most of the research and testing was done in the U.S., by American riders. The prototypes were ridden in the woods and deserts, east and west. When something broke, the parts were dissected, improved and tested again.
The KDX is assembled in America, at Kawasaki’s Lincoln. Nebraska plant. Engine and transmission and most of the running gear is shipped here from the home plant, but the chrome-moly steel frame, plastic fenders and fuel tank, aluminum sw ing arm. and K&Nair filter are made in the U.S.A.
Billed as an enduro machine, the KDX is a rather strange blend of enduro and desert. The 28° steering head angle is steep for dodging trees. Suspension travel has been kept moderate, 10 in. front and 9 in. rear, right forenduro use in mountains but a little short for cross-country. Seat height is a tall 37.9 in. Not a result of total w heel travel, but caused by the beautiful 7 in. thick desert seat. Gearing is also aimed at desert use: the bike will pull an indicated 95 mph on the stock 100 mph speedo.
Kawasaki has w isely made use of many lightweight motocross components like front and rear hubs, backing plates, drilled brake cams, hollow axles, dished head
bolts with thin nuts, and aluminum brake levers, head stay and engine plate. All of the plastic parts except the headlight/ number plate unit are American made. The airbox, front number plate and skid plate are made in Japan.
The frame is a conventional single downtube design with double tubes cradling the bottom of the engine, then turning up to terminate at the seat rail tubing. Triangulation is furnished by a pair of tubes that tie the backbone to the cradle just aft of the sw ing arm pivot. The steering head is well triangulated and heavily gusseted also.
The aluminum swing arm is a fresh new' design. It is basically an I-beam with the necessary cross members and shock mounts welded to it. Its general shape is odd. even ugly at first. Rather than stay a constant shape like we are used to, a large front section tapers to almost a point at the rear axle.
Suspension is by KYB. The shocks have remote reservoirs and spring preload adjustment but there’s no damping adjustment or rebuilding. They are mounted in a semi-lay down position. The non-radical mounting position combined with reservoirs make fading them nearly impossible. But. unfortunately their action isn’t very good by modern day standards. More about this later.
The forks are another story. Excellent, is the best way to describe them. Damping is the same as used on the KX 250 motocrosser we liked so much. Stanchion tubes are a beefy 38mm. travel is 10.0 in. They are air adjustable and their oil seals are protected with accordion type boots. Both triple clamps have double pinch bolts and the top clamp has rubber-insulated handlebar mounts. The bar mounts are rearset. so fork maintenance is easy. The stanchion tubes are a couple of inches longer than necessary so an owner can adjust ride height to change the bike’s quickness and handling. A cross country user may want to pull them down some to slow steering for those 90-plus runs across dry lake beds. Mountain users may want to adjust them shorter, to increase steering quickness.
The big KDX engine started life as a prototype 360 in 1976. It is an all new design, and has little in common with the old Ï975-76 KX400 engine. The head has radial fins and a hemispherical combustion chamber. The cylinder uses Kawasaki's patented Electrofusion instead of chrome or steel for the actual working surface. The surface is produced by exploding carbon steel and molybdenum w ire into the aluminum cylinder wall. Six explosions of 1.15mm molybdenum wire using 16.000 volts and nine explosions of 1.6mm carbon steel wire at 13.000 volts produce a porous Electrofusion surface approximately 0.070mm thick. The thin coating transmits heat quickly, allowing closer piston-to-wall clearance because the piston and cylinder expansion rates are similar. Closer piston-to-wall clearance also produces greater power.
Ports are large and plentiful. The exhaust port is bridged and has an o-ring located in its cast-in flange. The o-ring seals the pipe tightly to the cylinder so exhaust gases don’t leak out and water doesn’t leak in. This means the bike can be stalled in water deep enough to cover the exhaust port and the engine won’t fill with water. Not an important feature until you have spent an hour pumping water from a machine that filled its bottom end with water from around the head pipe.
A six-petal reed cage with Boyensen fiber reeds controls fuel from a 36mm Mikuni carburetor. A two-ring piston with arched intake skirt is used. The arch is mild and the skirt doesn’t have holes in it. The piston top has a wide squish band and the contours closely follow the head shape. The top ring is an L-shaped Dykes. The second ring is a conventional straight type. The crank halves are 90 percent full cut and an external flywheel CD1 is used. The large flywheels and CDI add low-end pulling power to the unit.
Transmission gears are large, engagement dogs are strong and all transmission shafts run on needle or roller bearings. In -gear starts are possible with primary kick starting. Primary drive is straight-cut gear.. The KDX clutch is a giant unit but weight has been kept to a minimum with extensive use of aluminum. Clutch plates, clutch basket, clutch hub. and top plate are aluminum. The complete unit rotates on caged needle bearings and shouldn't fail under the most severe use. The engine complete with sprocket, carburetor and kick starter weighs only 70.5 lb.
A nice contoured plastic skid plate protects the engine cases from rocks and things, yet is light and doesn’t protrude.
Footpegs and rear brake pedal are sawtoothed to prevent boot slippage. The shift lever is strangely shaped. It is a bent piece of strap steel that bends down and around the drive chain. The peculiar shape is necessary because the shift shaft seems to exit the engine cases at the wrong place. A normal lever would be quickly sawed in half by the chain. Folding lever ends, something we have come to expect on an enduro bike, are not supplied on the KDX. We didn’t snag or bend either but someone surely will.
Naturally, a high snake pipe is part of the KDX package. It is routed so it doesn't burn or interfere with the rider. It is held into the o-ringed exhaust port by two springs and mounted to the frame with rubber blocks in two places. The silencer is solidly mounted with two attaching brack-
ets and incorporates a spark arrester. Although the pipe is double walled and the silencer an adequate size, the KDX is fairly loud for an enduro bike.
Only a tall person will be able to sit on a KDX and put both feet on the ground in anything but a tippy-toe fashion. Tall meaning six-feet or more. By using a seat the same thickness as the KX250 motocrosser, the seat height could have been lowered by 2 in. and the motocross seat is as comfortable as any off-road seat around. We tried to install a seat from a KX on the KDX but the KDX seat rails are a tad wider than the motocrosser, making the swap impossible without frame surgery. After the bike had a couple hundred miles on it the seat started to break in and the riding position lowered. The excessive height is a real nuisance when trying to>
turn the machine around on anything but flat, smooth ground. Even tall riders may find their legs too short if they have to dab while turning around on a slope. When this happens the bike naturally turns upside down on the rider. Most of the Kawasaki’s competitors have kept the wheel travel on their enduro bikes down to nine or IO in. and the seat comfortable but not unnecessarily thick, thus keeping the seat height low enough to dab and paddle with their feet when necessary. As an example the Yamaha IT has a 34.5 in. seat height, an XR500 measures 34.6 in., a Maico Magnum is 35.6 in., and all of them have about the same wheel travel as the KDX. The extra tall seat does have a side benefit though. The seat to footpeg distance is almost 23 in.—21 in. is the average for most modern dirt machines—and the transition from a sitting to standing position is made much easier as a result.
The large volume fuel tank is properly shaped and doesn't interfere with the rider’s knees. It incorporates a stepped bottom, like the Suzuki PE introduced last year. The step makes room for pipe clearance and adds an extra half gallon or so to the tank capacity. The added capacity is at the bottom so a large volume of fuel can be carried without adding weight at the top of the machine. The petcock is a plastic unit made by Vesco. Down is on, across is off'. Simple and efficient.
The tank design is partly responsible for the bike feeling lighter than it is under way.
A couple of other things also contribute to this. The light Electrofusion cylinder keeps engine weight low' and the steep 28° rake also adds to the illusion. Steering is quick and the machine has an agile, go-wherepointed personality. It is a very solid mo torcycle and flex isn’t part of the package. Controls are properly placed and if the machine is stalled in a precarious spot, it has primary kick starting. Restarting is as easy as pulling in the clutch and jabbing the long slip-proof kick lever.
The frame has some little plates welded on the tubes by the swing arm pivot bolt that show great thought has gone into design of the KDX. The plates keep the rider’s ankles from being bruised on the bolt ends on rough ground.
Perhaps the person who designed the plates had ridden the KDX with the stock shocks. We had almost 200 miles on the bike before they started letting the rear wheel follow the bumps. Until then the back end bucked and hopped and pieces of angle iron would have worked as well. After break-in they were much improved and usable but still nothing great.
The large forks are as good as the shocks are poor. They never do anything wrong and their action is almost flaw less.
The KDX slides fire roads like it was designed to be a track bike. Full-lock slides are as easy as turning the throttle. The more the throttle is turned, the more crossed-up the slide. High speed corners on rough ground aren't as much fun. The shocks make control difficult but a good rider can still cover a lot of ground in a short time. Darting between trees and boulders is great fun on a KDX. It steers. Only European machines used to be so precise.
Horsepower is everyplace and anyplace between idle and top rpm on the big 400. Rated power is almost 40 and torque —the reason most people buy open class enduro bikes—is over 31 ft. lb. With figures like these the five-speed transmission is almost one more gear than needed. Even w ith the tall final gearing the bike has a gear for all occasions. Low will plunk around at a snail’s pace, fifth is good for an indicated 95. For full time use in forests, an owner will probably want to lower the overall gear ratios. As delivered the front sprocket has 15 teeth, the rear 48. Kawasaki has an optional rear sprocket two teeth larger and front sprockets from 13 to 16 teeth. The 13 with the stock rear will make the machine better for the woods rider. The big engine vibrates some but it isn’t enough to be annoying. It can be felt when sitting on the bike while the engine warms up but is almost undetectable once under way as the rubber bar mounts do their job and isolate it.
The KDX is an exceptionally good first year bike. The only things that keep it from being right-on are the shocks and the tall seat (if you are short). Aftermarket shocks will turn the bike into an instant enduro winner or fun play bike. Kawasaki is sponsoring Mike Hannon in national enduros this year on a KDX with minor modifications. Mike responded to the ride by winning the first national he entered. Are you ready to win?
KAWASAKI KDX400
$1799
