Motorcycle Mechanics 1977
AS the legendary 500 triple writhes in its final death throes, if it hasn't already sunk from sight altogether, the 400 takes over as Kawasaki's top of the line two-stroke. After the evil violence of the first Mach 1, it does seem a strange situation for big K to find them in, but then the 400 is the only one left with a hint of mean about it.
The exhaust note and the pick-up in the first three gears bear witness to its pedigree but much of the old character has been muted away. After riding the KawasakiKH400 it's hard not to think of it as a lightweight, a machine which performs like most people want their 250s to. It's equally hard not to think of the H1's or even the really malevolent H2 which paved the way for this survivor of the legislative 70s. Kawasaki's shop manual covers the KH and the S series — including the early 250s and the S2 350, the first of the slimmed down, domesticated triples. The 350 only appeared briefly in this country and hasn't been seen since the 400 first arrived. It's an odd state of development because the 350 was a much nicer bike. It was quicker, it handled really well, fuel consumption was no worse and it had lots of good detail design. I don't remember it being significantly noisier or smokier than the 400, which makes it hard to see why the slightly larger machine should be preferred.
These reminiscences aren't entirely irrelevant, if only as a basis for comparison. Briefly you could sum the machines up by saying that the KH400 is not quite as good as the RD400 while the S2 was that much better than the Yamaha.
It isn't just subjective opinion either, Kawasaki list the output of the S2 as 44hp at 8000 while they only claim 36hp at 7000 for the 400, with better claimed fuel consumption for the 350. Other differences are that the 350 had a shorter wheelbase by some 2 inches and weighed 30lb less.
Although the 400 isn't as quick as the 350, the handling is worse. Initially our model had a tendency to fall into slow corners — which was cured by playing around with the tyre pressures — and would weave rather too eagerly on long fast bends. The wide open spaces at the track made this much more noticeable, in the generally slower conditions on the roads the 400 felt a lot better.
Originally, with heavy steering caused largely by soft tyres, the triple was bad in slow bends and really had to be driven through bends and really had to be driven through, making pretty hard work of it. Suspension ravel is quite short and although the springs damping give a fairly comfortable ride, handling in general felt sloppy and imprecise. After increasing both pressures at the front and 2psi at the rear, the fault condensed into a more definable weave. This is exactly the same as our 500 racers — each improvement tightened up the weaving until we were left with a reasonably firm feel and a minor weave at high speed.
On the 400, it seemed that this is as far as you can go without changing the swinging arm — by trying to twist the wheel in the frame you can actually see the swing-arm flexing. NGK B8s are recommended but because we run the motor pretty hard on track and on the dyno we asked for a set of B9s, just in case they were needed. The day we picked the bike up we took it to the track and it just wouldn't pull full throttle — the plugs were a bright yellow. Having just collected the bike, we didn't know what fuel was in it (it turned out to be four-star) so couldn't tell if the plugs were fuel-fouling or just running too hot. Either way it seemed safer to stick the B9s in — it then ran perfectly up to peak revs in top and we left the plugs in for the entire test period. Even then, running it on 2-star fuel, in traffic and so on, there was no sign of any gassing up and cold-starting was invariably a second-prod affair.
The latest 400 A3 uses GDI ignition with no contact breakers. The only snag with cold starting was the warm-up. The triple needed bursts of choke tor two or three minutes after firing up. In theory this is no problem because the choke's a spring-loaded lever under the left twist grip. In practice it is not easy to work the choke, the clutch and hold out of the garden gate the motor would splutter and sulk, leaving the rider with a choice of grabbing the clutch and coasting info the road with a dead engine or jabbing the choke and risking a sudden burst of revs which would propel the bike forward with a great surge. The old S2 had a choke control positioned so that it could be used with the clutch — unless my hands have changed — and this retrograde development is in many ways typical of the 400.
The torque peak is spread from 5000 to 8000, which gives an ample spread of performance as long as the gears and revs are used. If the motor falls below 4000rpm it takes a long time to respond to the throttle and build up speed.
With a normally seated rider it will comfortably hold 80 to 90mph although above this speed the force getting to the back wheel drops sharply and makes top speed sensitive to wind, riding position and so on. Wearing an oversuit and sitting upright it was usually difficult to coax the Kawasaki much above 90mph. In leathers, getting flat on the tank, we ran it up to 101mph.
During the track test it didn't feel particularly quick and the handling seemed indifferent. This changed considerably when the 400 was used on the road — it was much more pleasant to ride, emitting the nice noises that only a triple can make. The handling felt quicker and matched the motor's smooth pick-up, the Kawasaki suddenly became fun to ride.
Only a few minor flaws marred all this. Second gear was a bit too low — or the top three ratios a bit too high —which made acceleration through the lower gears harsh and jerky. This shows up clearly on our road-load "cascade" curves, where second gear is set back from the lines of the other gears.
There was also some vibration from the theoretically smooth engine — felt mainly through the handlebar at middle-rpm but enough to make the left hand exhaust lose one of its retaining nuts.
The front disc is powerful enough but developed a squeal which steadily got worse as the test progressed and the combined horn/headlamp flasher was difficult to use.
Finally the fuel consumption averaged out at less than 34mpg; it was easy to get below this and hard to get much above it without a total sacrifice of the 400's performance. Oil consumption was better, on the whole the triple would give more than 200mpp. The crippling aspect of the fuel consumption was that the total range of the bike was only about 100 miles, including its reserve. Cruising at 70mph on a motorway would mean a fuel stop every hour or so.
Despite these niggles there was enough character about the KH400 to make it likeable, not very practical, but likeable. In a way the fact that the Kawasaki could ever be produced sums up the nature of motorcycling; as a mode of transport it doesn't score. But to a motorcyclist it still has that hard to define character which is all to do with romping along country lanes, swinging through roundabouts and buzzing lively motors up through their gears. This the Kawasaki does very well indeed.