Ktm 250mxc
KTM 250MXC
CYCLE WORLD TEST:
QUICK, LIGHT&EXPENSIVE
Uninvited, the tall, dark stranger wandered into our garage. “Good lookin’ KTM ya got there. Hmm, water-cooled and all. Never saw a water-cooled 250 enduro bike before. Do enduro bikes really need water-cooling?”
Good question. The answer that comes first to mind is no, they don’t. Given a little thought, the answer changes to maybe. Water-cooling would be wonderful if caught in a bottleneck in July, temperature 100 degrees. It might not be so wonderful if the radiator got speared by a tree branch, but we haven’t yet ruined a radiator on any of the many watercooled motocross bikes. And some, like the Suzuki RM250, got used several times in the desert and woods. Additionally, our experience with water-cooled MX bikes has proven the pistons and rings last three to four times longer.
Many top enduro riders prefer modified motocross bikes for competition, claiming lots of enduros are actually motocross through trees. The ’84 KTM 250MXC is exactly that, a water-cooled MX bike with a wide-ratio transmission and larger gas tank.
Built in a modern Austrian factory, the ’84 MXC250 is a beautiful machine; orange frame, white plastic, blue seat and trim. Light aluminum parts abound: the swing arm, shift lever, rear brake pedal, shock body, shock linkage, silencer, wheel rims, brake actuating arms and chain guide plates. Chrome-moly steel is used for the frame, handlebars and axles. A one-off custom couldn’t be built with better quality components.
Back to the engine. Last year’s 250 enduro used an old-style engine, a nice power plant but large for its displacement. The ’83 KTM motocrosser got a new, compact, water-cooled engine. Both models use the new engine this year. The cylinder is aluminum with a cast-iron liner. A large reed cavity in the rear of the cylinder contains a six-petal reed. The exhaust is piston-controlled, no moving valves or expansion boxes to alter torque. The exhaust pipe is the same as used on the MX model, ditto the silencer.
Compact magnesium cases contain a large clutch, outside flywheel Motoplat CDI ignition, and wide-ratio five-speed transmission. The water pump is driven off the primary gear and the water hoses are neatly routed to and from the dual, frame-mounted radiators. Most watercooled bikes have a bird’s nest of water hoses, the MXC doesn’t. There is a minimum of hoses, thanks to carefully thought-out water routing: a short hose from the pump to the cylinder, one from the cylinder head to the bottom of the left radiator, one between the tops of the radiators and one from the bottom of the right radiator to the pump. Water enters the bottom of one radiator, exits its top, enters the other radiator’s top, exits its bottom. And all of the hoses are formed, no straight hoses bent to fit.
KTM was the first manufacturer to use frames with bolt-on sections on motocrossers. The ’84 MXC has one too; removing four bolts gives access to the rear shock. The main frame appears strong enough for a 500cc engine. The backbone tube is huge and triangulated, a big front down-tube splits into two smaller ones just above the centered exhaust port, then wraps under the engine, ending at the backbone tube below the front of the seat. Small cast steel footpegs have strong return springs and open bottoms so they don’t fill up with mud. The frame is designed to eliminate the need for many gusset plates and the few it has are drilled to reduce weight.
Suspension, like the rest of the bike, is top notch. Forks are Marzocchi. Travel is 11.8 inches, stanchion tube size is 40mm. The lower legs are aluminum and contain flush-fit mud scrapers above the seals. Triple clamps have large clamping surfaces and pivot in caged needle bearings.
A White Power shock is used on all KTM models in’84.The new design has a piggyback reservoir (cast to the shock body rather than connected to it with hose) positioned on the left side of the bike. Compression damping is adjusted by turning a knob at the top of the reservoir. The knob is clearly marked from one to seven but the side number plate has to be removed to be seen clearly. Each position has a positive and audible click so it’s not much of a problem. Still, it’s probably best to remove the side plate the first time it’s adjusted. After that it can be reached from the bottom of the number plate. The standard position is number 1, the softest. We liked it best set at number 3, but then that’s why it’s adjustable. Rebound damping is also easy to adjust; the knurled knob is just above the lower shock clevis. Eleven positions are available, each a positive click. Additionally, the knob is clearly marked from one to eleven. Number 6 is the recommended starting point. It worked fine at that position.
Spring preload is adjustable and easy, especially with the sub-frame section removed. About 4 inches of sack (the difference between a measurement taken with the rear fully extended and then with the rider aboard) worked fine.
The aluminum swing arm is stronger and lighter for ’84. It has a rectangular box shape with tapered ends. For some reason, it’s painted silver. A bolt-on side stand tucks up under the arm where it’s out of the way but easy to operate.
Both wheel assemblies are strong and light. The hubs look like Yamaha YZ copies with larger spokes. The aluminum rims are manufactured in Finland (Nordisk). They are the same as Husqvarna uses but natural aluminum color. They feature deep centers which make tire changing easier. Tires are Metzeler, no complaint there. The brakes are truly different; double leading shoe at both ends.
All the plastic parts are nicely finished, thick and durable. The gas tank holds 3.4 gallons of premix (40:1 is recommended), the fenders are modern shapes and effective, the side numbers are stylish and fit well, the radiator scoops collect air but don’t protrude or catch on the rider’s knees. The hard seat has a mildly extended front that lets the rider slide forward easily since it doesn’t climb half way up the tank. Once forward, the rider actually sits on the back of the tank but it gives enough to be comfortable for the limited time a rider spends there.
Hand levers are split-perch Maguras with a more radical dogleg. They are better than the old style but still require large hands to operate comfortably. A dual-speed Magura throttle boasts a slow-actionenduro or a quick-pull motocross mode. The throttle has to be disassembled to change speeds but it’s something most riders will only adjust once. Changing the throttle cable is easier; the top of the throttle pops off, exposing the cable and pulley. And the cable end slips out of the pulley without disassembly of the throttle.
Enduro hardware is partly standard, partly optional. The shift lever end folds, the rear brake pedal has a good steel claw top that doesn’t. Rear wheel adjustment is motocross style, not quickchange or quick-adjust. The speedo drive is integral with the front brake backing plate so the drive unit doesn’t add another loose part to wheel removal/replacement. The MXC doesn’t have lights, speedo or spark arrester in stock trim. These parts are offered as options for those who want or need them. Desert enduro riders and those who only race hare scrambles, won’t want the option nor have to pay for useless (to them) equipment. Our bike came with the optional lighting kit and VDO speedo. The lighting kit is nice, the VDO speedo isn’t so great; the odometer numbers are small and hard to read and the needle jumps around. Adapting an odometer from an IT Yamaha would be a better choice.
Starting the KTM 250MXC is deceptively easy. The short kick lever is hard to push through its stroke due to a high internal gear ratio; it’s designed to spin the engine rapidly so a strong spark is generated from the CDI ignition. The trick is don’t push it through, stab the lever with a backward kick of the right foot, while standing next to the bike. The engine fires instantly. Starting a cold engine requires another special technique; it’s necessary to flood the Bing carb (no choke lever, just a flooding button) until the overflow tube has spilled gas for 5 or 6 seconds before kicking, ah, stabbing. If done right, the bike will start the first or second time.
The engine runs smoothly and no vibration is noticed while the engine warms to operating temperature. The clutch lever is easy to pull and the clutch releases completely. Engagement is smooth and quick without being grabby.
The engine makes excellent power; smooth, predictable and strong. There is a small flat spot just above idle before the engine gets into the powerband, then power rushes out in an unruffled progression. Shifting is smooth and precise as long as the rider uses the clutch or backs off the throttle slightly. Otherwise the transmission will balk before it changes gears. The clutch approach is best; just touch the lever with one finger as a shift is made, it’ll slide into the next gear quickly and positively.
The controls are positioned well and work properly, except for the rear brake pedal. It is tucked in tightly to eliminate catching on berms and tree roots, so the rider has to turn his toe in to operate it. We bent it out slightly and lowered it. The brake pedal is pretty but not the best design we’ve seen. If adjusted low enough to be comfortable, there’s not much distance left between the bottom of the lever and the frame. Use caution when setting the static height and it won’t be a problem.
Handling through the trees and crooked stuff is wonderfully quick and controlled. The bike turns and changes direction with ease, yet never feels too quick. Like previous KTMs, this one has suspension that’s a little stiff from the shipping crate. It takes about 100 miles to get the suspension parts working smoothly. We recommend not changing the shock adjustments until the bike is ridden the first 100 miles or so. After that, the fork and shock seals loosen and the bike becomes comfortable. The forks work better than any Marzocchis we’ve tested. They respond to small bumps without bottoming on large ones. The White Power shock is also very good. It can be adjusted to perform as the rider> wishes. Most riders most of the time will like the suspension adjustments in the middle of their ranges, making the bike easy to set up softer or harder for different conditions.
Balance is exceptional. This bike has the ease of a 125 motocrosser. It’ll dive under most bikes in tight turns without the rider straining. The front tire never skates or washes and the bike never scares the rider due to bad manners. Lofting the front wheel over logs is as easy as twisting the throttle a little farther or hitting the clutch. Once up, the bike runs straight and true and doesn’t try to loop. The powerful engine pulls the gear spread well until shifted to fifth. There’s a noticeable jump in the ratios from fourth to fifth. Winding the engine before shifting to fifth eliminates the lag. The rest of the gears, first through fourth, are well matched to the engine’s power and there is a gear that’s right for every trail use.
The double-leading shoe brakes were disappointing at first. They didn’t stop the bike well without a lot of lever force. We took a few minutes to seat them by riding the bike on smooth ground with the brakes lightly applied. We used an abandoned section of pavement and rode the bike at 40 mph, dragging one brake until it heated, then the other. After they got good and hot we let them cool for a few minutes, then repeated the procedure. Both worked well after that. The front brake still requires a little more lever force than comparable Japanese brakes but it’s not objectionable. The front is progressive and has good feel. The rear requires a lot of lever force and doesn’t give the rider much feed-back as to what is happening. Hard brake lining is the culprit. We disassembled both brakes and discovered Yamaha YZ 250/ 490 front brake shoes (dual leading shoe 1983/84 models) fit perfectly. And, the lever force is reduced significantly, thanks to the softer brake lining.
The 1984 KTM 250MXC is a fine bike that gets better as the miles pass. If you’ve been lusting after the factorysponsored pro’s water-cooled enduro bikes, lust no more. Your KTM dealer can sell you a production bike that’s just as good. Just ask for an ’84 KTM 250MXC.
$2820
