YAMAHA XS400D
Cycle World Road Test
More Flash and Extra Spunk Combine to Make a Sporting Commuter
Just what is it about mid-displacement four-stroke Twins that endears them to so many members of the motorcycling population? Many things, from economy to ease of maintenance to reliability to peppy performance, plus an added bonus of a fairly low initial cost; all important factors that spell success in terms of sales.
Honda was first to pick up this idea and market the proper instrument in the form of the CB350, which outsold every motorcycle on the market and created a segment of the marketplace that belonged to them and them alone. When they upgraded to the CB360, Kawasaki was next in line for a piece of the action, debuting their KZ400 Twin, another instant sales wonder. We knew it wouldn't be too long before Suzuki and Yamaha followed, Yamaha beating Suzuki to the punch, the whole affair turning into a battle of giants.
Now while Honda has been going along fine with a 360, Kawasaki and Suzuki with 400s sort of one-upped Honda and Yamaha. We would pretty much bet it won’t be long before Honda announces something along the lines of a 400 Twin to keep up with the rest of the gang, since here we have Yamaha springing theirs on the world, leaving Honda back there all by itself. And we should note here that all except Suzuki build economy versions, minus amenities such as electric starting, disc front brakes and so forth.
Yamaha’s 400 is the flagship of their mid-displacement Twins, carrying not only the extra engine size, but disc brakes front and rear, aluminum wheels and other goodies. It’s like a Chevy Biscayne with a big engine and deluxe trim.
Motorcycles in this category, despite their popularity, are beset with a basic problem: vibration. Twin cylinder four strokes shake, and the larger the displacement, the greater the shake. This is apparent with the new Yamaha XS400. It vibrates quite a degree more than the XS360, the one trade-off for the extra performance. Its larger pistons (bore size was increased to gain the displacement) produce more shake, simple as that. For some of our staffers this extra vibration was objectionable, others overlooked it and enjoyed the extra performance.
If one is used to riding a 500 cc and up motorcycle, the 400 is going to seem small in comparison, but after a few miles in the saddle the toy-like feeling will disappear and the machine will feel like a real motorcycle. The XS400 is more than capable of carrying a hefty size rider or two average size riders, an important fact to consider, and another reason why the mid-displacement Twins find a wide variety of acceptance among motorcycle owners. Big enough to do the job but not big enough to be complicated and costly.
The mild steel frame is sturdy and rigid so things don’t flex when pressed to the limit. Though the XS wasn’t designed to be a mountain road stormer, many of the people who buy the motorcycle will discover they can have much in the way of fun on their local twisty road. Ground clearance is adequate and geometry is about right until one really starts winging it. Then the short wheelbase, steep fork angle and short trail manifest themselves in the form of twitchy response; the handling is just a bit too quick for those who are somewhat clumsy in their movements. But around town these characteristics are welcome, the XS is a breeze to throw around and can work its way through traffic like a hot knife through butter.
SUSPENSION DYNO TEST
FRONT FORKS
Description: Showa fork, HD 315 oil Fork travel, in.: 5.0 Engagement, in.: 6.0 Spring rate, lb./in.: 25 Compression damping force, lb.: 6 Rebound damping force, ib.: 28 Static seal friction, lb.: 11
Remarks: The XS400 fork is right. Damping and spring rates are ideal for a bike of this weight. An FEP (Teflonish) impregnated slider bearing is incorporated, improving rigidity while decreasing dynamic friction. No changes are necessary.
REAR SHOCKS
Description: Rear shock, gas/oil mix, non-rebuildable. Shock travel, in.: 3.0 Wheel travel, in.: 3.6 Spring rate, lb./in.: 100 Compression damping force, lb.: 11 Rebound damping force, lb.: 97
Remarks: Damping rates of the stock shocks are appropriate, but the spring rate is excessive. A set of 80 lbs./in. springs should make the rear end of the bike a solid match for the front. Tests performed at Number One Products
To curb some of the vibration for the rider, handlebars are rubber mounted but not enough to make them feel spongy. Footpegs are thick rubber and the brackets holding them are also cushioned from vibration. Yamaha seats these days are excellent and this also plays a big part in keeping the rider happy. Underneath the saddle are electrical items and a small storage space. The seat locks in place and has a small device to hold a helmet safely while the rider is away from the machine.
Handlebar switches and controls are first rate all the way, from the soft rubber handgrips to the self-canceling turn signals. Turn signal lenses are amber for high visibility, the big, bright taillight has two bulbs and instruments are easy to read. Enough can’t be said about the excellence exhibited here. The only item Yamaha might want to improve is the headlight capability as most motorcycles with a few exceptions all need stronger headlights.
As one would expect, braking is more than adequate, the rear disc really not needed but there all the same, so what the heck, it looks good and allows use of the aluminum wheel. These wheels also look
good and are truer and more rigid than spoke wheels and definitely easier to maintain. The Bridgestone tires are okay for average work, but should be replaced by those seeking more traction and greater mileage from their rubber.
We’ve been applauding Yamaha suspension for more than a year now and it’s nice to say we still are. Our data panel will give you the specifics, but we can say here
that little is left to be desired in terms of a comfortable ride and decent handling. Heavier riders who go hard should look to aftermarket shocks, but even the Stockers work quite well to a point, then allow some wiggle to creep in as speeds creep up. The forks we’d leave just as they are.
Over the little freeway jolts and at intersection dips the forks take it all in without hardly letting the rider know what’s happening down there. And the standard shocks provide a surprising amount of the right kind of damping for soaking up bumps properly, though the spring rate should be juggled with.
Basic styling is the same as the XS360 save for paint and the special wheels. It’ll be interesting to see just how many buyers will spend the extra bucks and spring for the 400 over the 360. And we wonder how long the 360 will stay in production competing so closely with the 400. One would think that it’s expensive to produce three different models of the same kind of bike, which is basically what is happening here.
That extra displacement adds up to quite a bit more in acceleration. Figure on nearly a second quicker in the quarter mile and five miles per hour or so in top speed. As we found at the drag strip, the 400 will literally trounce a Honda 750 Automatic, for those who like to thumb their noses at larger machines. Fuel mileage remains close to identical as well.
Part of the reason the machine is so responsive is carburetion which allows the engine to accelerate from just off idle to redline in sixth gear without so much as a stumble. The twin 34-mm Mikunis are the constant velocity variety and they allow the engine to pull cleanly. Their bad side is the tendency to allow the engine to unrev very suddenly and quickly, making it important to pay attention to the way one twists their throttle hand.
Row through the gearbox and the engine can be kept humming right at the redline. It’s a machine that comes across with performance, but in an unexpected way. Remember, this is supposed to be a middle-of-the-road transportation bike with some deluxe trim thrown in. But there’s no question that it is the king of its class when it comes to speed, and that class includes Suzuki’s GS400 double-overhead cam Twin.
As a single-overhead-cam engine, the 392-cc unit is what we would expect from Yamaha, though with less complication than they’ve been known to present us with in the past. The crankshaft is one piece and turns in three plain bearing mains. Connecting rods also have plain bearings on their big ends and the overhead camshaft turns in plain bearings as well. The ignition points are driven off one end of the cam, which of course is chain driven from the crank down below. Electric starting is quick and easy. The engine requires only a brief warmup before it’ll chug down merrily the road.
None of the machines in this category are terribly exciting but they’re designed to deliver lots of trouble-free riding while keeping expenses down. We think the Yamaha XS400D is the most exciting machine in the class and will deliver what the buyers of this type of machine are looking for.
YAMAHA
XS400D
