Kawasaki 350 Avenger
KAWASAKI 350 AVENGER
CYCLE WORLD ROAD TEST
HAVING NICELY SEWED UP the small bike market, the inventive Japanese have set about to dabble with the passions of the big-bore road rider. Thus arrives the second 350cc Japanese rotary valve two-stroke in as many months - the Kawasaki Avenger. Kawasaki's 250 Samurai tested last winter was pretty hot stuff, like some of its sporting competitors. But the saying goes, "There is no substitute for cubic inches, except more cubic inches."
The new Avenger appearing in the medium displacement category (which is pretty large for our friends across the Pacific), must be regarded as a real pistol. It has all that the Samurai had, and more. It comes on stronger, with more available torque in the higher gears, and it does such un-Oriental things as lifting the front end coming out of corners. The 350 is a high performance touring machine, suited more to the knowledgeable rider who knows when to leave it off as well as turn it on than to the tyro.
To allay fears that the Avenger's engine is only a punched-out version of the 250 Samurai, it should be noted that Kawasaki started out to make a 350cc motorcycle in the first place, and then stopped to produce the 250cc machine "along the way," so to speak. Hence, there is a great similarity in scale and design of the two engines. The Avenger is a dual rotary valve two-stroke twin, with the crank assembly running on four ball-type main bearings, and needle bearing lower end. Both the Samurai and the Avenger have the same stroke, 56mm, and the increased displacement in the Avenger is achieved by increasing the bore from 53 mm, slightly "undersquare," to an oversquare 62mm, which gives a displacement of 338cc. The basic configuration of the engine, including gear and bearing sizes, remains the same. A heavy-duty clutch, however, has been added to take care of those extra "inches."
We particularly like the intake arrangement on the Avenger. Consisting principally of a large sound-damping casting, the air intake tract also houses the electrics, affording them a constant cooling flow of air, and dampens the intake sound so well that it is scarcely ever objectionable, even at full throttle opening.
The gear-driven generator, which runs at half engine speed, also provides drive power for the ignition breaker points. An indexed plate, fixed to the end of the generator, provides accurate ignition timing when it is lined up with a fixed pointer that corresponds to 23 degrees of ignition advance. This arrangement is decidedly better than a breaker assembly mounted on the end of a crankshaft where, because of lack of support, it can permit timing to wander.
An important difference between the Samurai and the Avenger is the lubrication system. Readers will remember that the 250 is fed by an oil injection system in which oil, separate from the gasoline, is metered into the gas at the intake port, relying upon crank chamber "swirl" for proper distribution to bearings and cylinder walls. In the 338cc Avenger engine, this intake port oil-gas lubrication is supplemented by direct oil injection to the crankshaft bearings and connecting rod big ends, in the interest of coping with the greater power produced. This system, called Injectolube, is an offspring of the system necessary on the more highly stressed 247cc AIR, the road racing version of the Samurai. The metering system works well, and there was no evidence of excessive oil expenditure.
The 350 starts easily, even on cold days, with the use of the handlebar choke lever. One good feature of the Kawasaki choking system is that it raises the idle of the engine slightly; useful, if one has to roll off while the engine is cold and the clutch is still dragging.
While large bore two-strokes are not noted for their economy, the fact that the Avenger, with a 7:1 compression ratio, uses regular while still developing all that horsepower, will provide some solace. We did notice more vibration in the 350 engine than in the 250.
The double cradle frame and rolling gear are similar to the Samurai. A few styling changes are evident — notably, the chrome panels on the fuel tank, the stubby stinger tips in the silencers, the covered rear spring units and the nice American-style pleated seat. The Avenger looks good and it looks big.
On the road, it has a big bike feel, but no suggestion of excessive top hamper. Springing is stiff but rarely jarring. It handles very well, laying over and tracking with good stability and precision.
The brakes are excellent and it is amazing how fast one can repeatedly pull this bike down to a dead stop from high speed. The front brake squeaked slightly, perhaps because it was not properly bedded in, and it was also overly sensitive to first application, then becoming spongier as braking progressed. While this feeling did not seem to be a product of fade, it did tend to mislead the rider into setting the front brake adjustment too loose.
The power characteristics of this engine are unusual and offer pleasant surprises. Peak range spreads generously from 6,000 to 9,200 rpm. In the 60 to 70 mph range, high gear is still turning the engine at the bottom of the power band, so the Avenger may be spurred on upwards with a simple twist of the grip. For optimum acceleration, one drops into fourth for a surging rush past 80 mph. In fifth, the machine feels like it is loafing at 80 mph.
The unusual part is that the Avenger may be driven comfortably from 2,000 to 6,000 rpm, and still has enough torque at these engine speeds to make it useful in traffic. The advantage of a useful low rpm range, of course, is that you aren't plagued with high buzzing sounds when all you want to do is calmly motor through town. Third and fourth gears at speeds of 35 to 45 mph felt quite comfortable.
The gear ratios utilize the engine's peak powerband well and there are no outrageous jumps from one gear to another. The gap properly gets narrow in the higher gears to compensate for increasing wind resistance and rolling friction. Accordingly, one is never quite "off the pipe" when demanding the utmost from the bike.
As one can see, the acceleration times are impressive, to understate things. A 14.4-second quarter mile at 94 mph has been something for 500s and 650s to covet, not 350s.
There is not much chance, however, that the A-7 in your dealer's showroom will have the performance of our road test machine. Investigation showed the crankcase inlet ports have been opened 1.5 mm, front and back. The rotary valve cutaway has been increased to advance the opening by 25 degrees, giving a total duration of 137 degrees. These are the only changes from standard, and they account for the peaky performance and relatively low power at the bottom end.
To compensate for loss of low end power, Kawasaki has fitted a rather low overall gearing to the Avenger; in fact, almost the same gearing as on their 250 Samurai. And, although normal red line is 8,750 rpm the intake changes cause the engine to go well beyond red line with considerable eagerness — so much so that we chose 9,250 as maximum revs for our test.
One consolation is that anyone with a rotary file can convert his A-7 to match the test figures. The engine will, of course, have to be dismantled to prevent swarf in the bearings. ■
KAWASAKI
350 AVENGER
$815
SPECtFJCAT1O:N~
:FiERFORIMANCE
