Driving report Yamaha YZ 400 F

Driving report Yamaha YZ 400 F


Times are changing: Small four-stroke crossers will come and really heat up the sedate steam hammers like the poisonous two-stroke vehicles. Yamaha is paving the way with the new YZ 400 F..

Two-stroke engines are aggressive and easy to handle, four-stroke engines are gentle and cumbersome.

Typical pigeonhole thinking, but so far it has worked to some extent in the cross area. Soon, however, the cross fans will have to rethink, because with the YZ 400 F Yamaha brings a motorcycle that cannot be pressed into familiar templates at all. The test drive with the factory crosser, which was successful in the world championship, gave an idea of ​​what the off-road community could expect (driving report MOTORRAD 21/1997). However, the uncertainty remained as to how much of the potential of the factory machines, which had been built with incredible effort, would remain in the series. MOTORRAD was able to gather first impressions at an exclusive test appointment.
At first there was skepticism: no milled parts, no carbon fiber, no titanium, instead of refined delicacies unspectacular home-style cooking. There are also many differences behind the scenes. The displacement is the same, but the stroke is four millimeters longer. In contrast to the factory machine, a balance shaft calms the five-valve engine and the significantly larger oil supply is bunkered in the frame.
So disillusionment instead of fascination? Not at all. The enthusiasm is already there after a few laps. The little thing with the dimensions of a 250 is in some ways even better than the hand-carved model. The almost vibration-free YZ 400 F delivers almost as much peak performance, and the usable belt is even wider. Even from the lowest engine speeds it accepts full throttle without any problem. Brutal power from the cellar is not, but at least the four-stroke YZ bravely starts. In the middle speed range – so at 5000 to 6000 / min – then comes the hammer. The performance grows dramatically, the usable band is enormous. There is always a lot of power up to the highest regions, an end to the speed orgy can hardly be seen.
The best, however, is not the performance, but the way in which it starts. No other four-stroke engine behaves so spontaneously and directly, every minimal turn of the throttle is implemented without delay. A small ramp is enough to jump over a series of mean washboard waves in which a sluggish displacement giant would mercilessly crash. With the large four-stroke engines or the 500 two-stroke engines, one looks in vain for comparable characters. Parallels can only be found in 250cc crossers, the lap times are also at this level.
Despite all the euphoria, a few small points of criticism should not be forgotten. When kicking off, the YZ 400 F is not very cooperative despite its small displacement. The mixture wants to be compressed to less than a twelfth of the cylinder volume with the kick starter, so you have to push hard. For tricky cases, like the racing model, there is a hot start button that lets fresh air directly into the intake duct.
F.In terms of movement, the YZ cannot quite keep up with the factory crosser. The fork hits hard when braking, it seems a bit soft. The result is a tendency to hit the handlebars from time to time. Maybe just a question of tuning, that can only be clarified by a detailed test. Those who are curious don’t have to wait long for it, as delivery to dealers should begin in December. Only one question remains: will Yamaha be able to deliver enough copies of the new wonder weapon?

Technical specifications

Yamaha YZ 400 FTechnical dataMotorWater-cooled single-cylinder four-stroke engine, two overhead camshafts driven by chain, five valves actuated by bucket tappets, wet sump lubrication with oil pump, Keihin FCR flat slide carburetor, Ø 39 mm, contactless capacitor ignition (CDI), kick starter bore x stroke 92 x 60.1 mmHub volume 399 cm³Nominal output 55 PS at 9000 / min torque Max. Speed ​​11,000 / minCompression ratio 12.5: 1Power transmissionPrimary drive via gears, multi-disc oil bath clutch, five-speed gearbox ChassisSingle-loop frame made of tubular steel with split lower bars, bolted rear frame, upside-down fork, standpipe diameter 46 mm, with adjustable rebound and compression damping, two-arm swing arm made of aluminum profiles, central spring strut, articulated via a lever system, with adjustable spring base, rebound and compression damping, front disc brake with double-piston caliper, Ø 245 mm, rear disc brake with single-piston caliper, Ø 220 mm, spoked wheels front: 30 0 mm rear: 315 mm Tire size front 80 / 100-21 rear 110 / 90-19 Dimensions and weights Weight without petrol 107 kg Tank capacity 8.7 liters Wheelbase 1490 mm Steering head angle 62.5 degrees Price 12 690 marks

The enduro version – tough competition for European sport enduros

KTM, Husaberg and Husqvarna have so far been among themselves when things get tough off-road. Yamaha wants to break into this phalanx with the blue-painted WR 400 F, an enduro version of the YZ 400 F. The two versions differ only slightly. The engine remains untouched and should therefore be just as agile and powerful. An alternator feeds the mandatory lighting. The twelve-liter tank increases the range for longer stages. The WR can spend breaks on the side stand. In addition, there is an 18-inch rear wheel, a wider gear ratio and a quieter silencer. The WR is not a street enduro, but a thoroughbred competition machine. As a result, it is not homologated in this country, but must be approved by dealers in individual purchase. It has not yet been determined with what performance and at what price.

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