Article: 19710101035

Title: 1971 KAWASAKI MACH III

19710101035
197101010035
CycleWorld_19710101_0010_001_0035.xml
1971 KAWASAKI MACH III
The Giant-Killer Has Been Significantly Refined.
0011-4286
Cycle World
Bonnier
CYCLE WORLD ROAD TEST
36
36,37,38,39
article
IT HAS BEEN more than a year since Kawasaki’s Mach III was first introduced. It is “only” a 500, but thanks to its advanced three-cylinder design, it was immediately classed with the Superbikes having displacements up to 900cc or more. We cannot forget the shattering impression it made upon us—smoking the tire and clawing away from the starting line to turn more than 100 mph in the standing-start quarter-mile.
Diagrams
Graphs
Photographs
36
37
38
39

1971 KAWASAKI MACH III

CYCLE WORLD ROAD TEST

The Giant-Killer Has Been Significantly Refined.

IT HAS BEEN more than a year since Kawasaki’s Mach III was first introduced. It is “only” a 500, but thanks to its advanced three-cylinder design, it was immediately classed with the Superbikes having displacements up to 900cc or more. We cannot forget the shattering impression it made upon us—smoking the tire and clawing away from the starting line to turn more than 100 mph in the standing-start quarter-mile. Even now, it is an astonishing machine, having the performance of a Grand Prix racer in full touring regalia.

The Mach III is not a racer, but a fairly tractable machine for the sporting street rider. In its latest version for 1971, it does its job even better, with a notable improvement in handling.

Media
Media
Media
Media
Media
Media
Media
Media

REFINEMENTS ABOUND

Changes are many. The front fork spring rate has been increased and the return dampening is somewhat greater than in previous models. Minute bumps in the road surface are not followed quite as closely as before, but larger bumps, especially those encountered when cornering, are taken with much more security. Gone is the slight tendency for the front wheel to “pogo”-a welcome deletion.

The rear shock absorber units have been changed to greatly increase dampening. These improve high speed stability to an enormous degree, both when riding solo and with a passenger aboard. Cornering power is also increased, due to the use of new (for Kawasaki) Dunlop profile tires.

Farther up the fork, we find that the handlebars are now mounted with a different rubber compound, but vibration above 6000 rpm is still quite noticeable. A softer compound seems to us the best cure, as the standard mounts are quite rigid.

A longer oil pump cable is now fitted and the oil pump pinion now features a lock to preclude its becoming disconnected, which would not only interrupt the flow of oil into the engine, but would render the tachometer inoperative.

On the left-hand-side crankshaft oil seal, a circlip has been installed because some owners were experiencing trouble with the seals popping out.

CDI UNIT MODIFICATIONS

The ignition system has received much attention. Earlier versions of the CDI units gave trouble because water seeped into the distributor setup through the wiring harness. The harness emerged from the cavity on the right side of the engine on the inboard side, and was routed between the right and middle cylinders. Last year the entire distributor cover was redesigned; the ignition leads now come up out the top of the right-hand outer cover.

Other improvements to the ignition system include an improved signal pickup. The older one had insufficient insulation surrounding it and heat caused it to fail rapidly. The mounting ears have been increased in size to withstand the torque American mechanics use when adjusting them.

Improved components are being used in the A and B boxes of the CDI system, and a perforated heat shield now covers them under the seat. This prevents riders from covering the system with rags or gloves, which could cause the delicate parts to overheat.

Because of the premature stretching of the rear chain, Kawasaki has gone to a chain with 0.2mm wider outer plates. The inner width remains unchanged.

Inside, the gear change drum positioning plate’s shape and material have been altered slightly to give more positive and reliable shifting.

PORTING AREA FOR POWER

The secret of the Mach Ill’s performance, strong even when matched against other two-strokes, lies in the use of three cylinders. For each extra cylinder wall, more port area is made available. Increased porting area allows increased transfer of fuel mixture into the combustion chambers, yielding more power. On paper, the advantage of three cylinders over two, in terms of porting area, is about 25 percent. The three-cylinder design, with crankshaft throws set apart at 120 degrees, also is an inherently smooth one.

Kawasaki’s Three is of the usual piston port variety, rather than rotary valve. While this may seem a curious tack for one of the pioneers in big-bore, rotary-valve, two-stroke design, the

Media
Media
Media
Media
Media
Media
Media
Media

reversion to piston-controlled port opening was necessary. It avoided unnecessary complication in cylinder and carburetor layout, and allowed the designers to hold engine width to a minimum.

The customary “bridges” of the intake ports have been removed, with only short, radiused tips protruding down from the tops of the ports. Port timing hasn’t been changed, but the absence of the bridges seems to have helped engine breathing. Size of the exhaust pipe studs has been increased from 6 to 8 mm.

With increased performance, fuel economy suffers somewhat. As a result, the Mach III rider will get only 110 to 120

miles on a 4-gal. tank of high-grade gasoline. This is somewhat unfortunate, as the 500 ranks high in almost every other respect as a long-distance tourer.

It cruises effortlessly at 80 to 90 mph, and is rock-steady in a straight line at even higher speeds over average quality country highway. While the three-cylinder firing pattern at first gives an illusion of excessive rpm at legal freeway speeds, you quickly become accustomed to it. The noise level is moderate, produced more from intake moan than from the exhaust. It is not irritating, if you are riding steadily, and, presumably, you will be so busy that you won’t notice the racy howl it sets up when you get on the gas hard.

POWER AND HANDLING

The Mach Ill’s power band comes in at 5500 rpm and keeps wailing right past the redline until approximately 9500 rpm. While most motorcycles are set up to barely pull red-line, or just below it, in top gear, the Mach III seemingly could pull a much taller gear. Our top speed run was conducted with the Three overrevving mightily past the 8500-rpm safety limit. As it is, the present gearing provides the right amount of flexibility for both in-town and highway riding.

High speed handling on mountain roads and the like is good, though the bike is somewhat reluctant to be thrown down in a bend. It must be put there with malice aforethought. Once there, it was steady. Try as we may, we could not induce any of the wobbling about which some owners of the first Mach Ills were complaining. The most we could get was some mild twitching at the back end, the sort you can expect from any machine not set up specifically for road racing. The center stand grounds quite easily, however, and becomes a definite nuisance in two-up riding.

Both rider and passenger will find themselves quite comfortable. The handlebars are positioned well, and their relationship to the rider’s seat and to the footpegs fit both the tall and short members of the staff well. One of our soft-fannied friends, an expert in pillion passengering, rates the rearward position on the Mach III as better than on some machines more commonly associated with two-up touring. There’s lots of room for her to get weight on her legs and keep her back in a position where it doesn’t ache after a long day.

EVIDENCE OF BRAKE FADE

The Mach Ill’s one weakness seems to be its brakes. While stopping distances are good, there is evidence of fade after repeated stops from high speed. Or during a rapid trip through the mountains. Feedback from the front lever is deceiving. You don’t get a steady increase in braking power for a correspondingly steady increase in hand squeeze. The rear brake pedal also is insensitive. You must make a conscious effort to press it, although it does generate considerable stopping power, and fades less than the front.

All the other aspects of the Mach III, with the exception of braking and fuel consumption, make it an extremely pleasurable mount in day-in, day-out use. It starts easily, with one or two jabs at the kick starter on cold mornings. The choke lever is positioned near the throttle grip, so the thumb may push it, using the same direction of hand rotation used to open the throttle. Warm-up is quick, even on cold mornings, and the Mach III, an oil-injected two-stroke, showed only a little smoking, even during the warm-up period.

When it was introduced, the Mach III amazed all with its blistering performance and engineering audacity. Now Kawasaki has begun the task of refining the design. As a result, the 197! version will surprise buyers'for those “quieter” forms of amazement—reliability, consistency, and livability. [Ö]

Media
Media
Media
Media
Media
Media
Media
Media

1971 KAWASAKI MACH III

SPECIFICATIONS__

List price ..........................$995

Suspension, front ............telescopic fork

Suspension, rear ..............swinging arm

Tire, front .......................3.25-19

Tire, rear ........................4.00-18

Brake, front, diameter x width, in. ... 7.9 x 1.4

Brake, rear, diameter x width, in.....7.1 x 1.4

Total brake swept area, sq. in.............65

Brake loading, lb./sq. in................8.39

Engine, type ..............two-stroke Three

Bore x stroke, in., mm . . . 2.36 x 2.31, 60 x 58.8

Piston displacement, eu. in., cc ......30.4, 498

Compression ratio ...................7.0:1

Claimed bhp @ rpm ..............60 @ 8000

Claimed torque @ rpm, Ib-ft......42.3 @ 7000

Carburetion ........... (3) Mikuni VM 28 SC

Ignition ................capacitive discharge

Oil system ................... . oil injection

Oil capacity, pt........................5.0

Fuel capacity, U.S. gal..................4.0

Recommended fuel ...............premium

Starting system .......... kick, folding crank

Lighting system ............. 12-V generator

Air filtration ...................poly-foam

Clutch .....................multi-disc, wet

Primary drive........................gear

Gear ratios, overall:1

5th .............................5.84

4th .............................6.66

3rd . ............................7.90

2nd ............................10.15

1st ............................15.95

Wheelbase, in........................56.0

Seat height, in.......................32.5

Seat width, in........................10.5

Handlebar width, in...................31.0

Footpeg height, in...................11.75

Ground clearance, in...................6.0

Curb weight (w/half-tank fuel), lb........418

Weight bias, front/rear, percent........ 43/57

Test weight (fuel and rider), lb...........548

TEST CONDITIONS_

Air temperature, degrees F ..............77

Humidity, percent.....................62

Barometric pressure,.in. hg.............30.08

Altitude above mean sea level, ft.........350

Wind velocity, mph ....................6-8

Strip alignment, relative wind:

Media
Media
Media
Media

PERFORMANCE_

Top speed (actual @ 9600 rpm), mph .... 124.8 Computed top speed in gears (@ 8500 rpm), mph:

5th ............................. 110

4th ..............................97

3rd ..............................81

2nd ..............................64

1st ..............................40

Mph/1000 rpm, top gear ...............13.0

Engine revolutions/mile, top gear .......4610

Piston speed (@ 8500 rpm), ft./min...... 3265

Lb./hp (test wt.) ......................9.1

Fuel consumption, mpg.................32

Speedometer error:

50 mph indicated, actually ...........47.9

60 mph indicated, actually ...........56.9

70 mph indicated, actually ...........67.4

Braking distance:

from 30 mph, ft....................35.5

from 60 mph, ft...................138.7

Acceleration, zero to:

30 mph, sec........................2.0

40 mph, sec........................2.4

50 mph, sec........................3.9

60 mph, sec........................4.4

70 mph, sec........................5.7

80 mph, sec.............. 6.9

90 mph, sec........................9.1

100 mph, sec......................13.6

Standing one-eighth mile, sec.............7.5

terminal speed, mph ................86.4

Standing one-quarter mile, sec..........13.22

terminal speed, mph ...............98.03

Media
Media
Media
Media