Ten days with a 1975 Kawasaki S3 Mach 2

The Classic Experience


Though not as raucous as its bigger brothers, the Kawasaki S3 Mach 2 still has plenty of attitude.

Photo by Richard Backus

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Kawasaki S3 Mach 2
Years produced:
Claimed power: 42hp @ 7,000rpm
Top speed: 97mph (period test)
Engine type: 400cc, air-cooled, two-stroke inline triple
Weight (dry): 155kg (339lb)
Price then: (1975) $935
Price now: $1,000-$2,000
MPG: 22-35
Oil consumption: 1/2qt two-stroke oil during test
Beginning miles: 2,925
Ending miles: 3,283

If you’ve never ridden a classic two-stroke, you owe yourself the experience. Generally smoky, smelly and loud, they pay back in spades with a power rush you have to feel to appreciate. And that’s just with a healthy single: multiply that count by three and the payback is a thrill a mile.

We sampled a 1975 Kawasaki S3 Mach 2 - one of the tamer (and better) of Kawi’s three-pot oil-burners over the course of a few weeks - and when it was all over, we hated to give it back. Our test bike is the kind of machine we all dream of finding. Its first owner rode it a little over 1,000 miles before passing it along to his son, who then parked it in his garage where it sat until 2006. Its current owner then acquired the bike for $150. Yes, just $150. But more on that later. 

In the beginning…
Before 1969, Kawasaki was a just a bit player on the American scene. With a quirky line of two-stroke singles and twins, its biggest standout was its BSA-clone W1 and W2 650 twins. But that all changed when Kawasaki introduced the three-cylinder Kawasaki H1 Mach III in 1969. With a claimed 60hp from its 498cc three-cylinder, two-stroke engine, it was just the thing for a power-hungry market. Suddenly, Kawasaki was no longer an also-ran; the Mach III’s 120mph top speed and 0-60 time of 4 seconds made it the king of the drag strip and the fastest production motorcycle on the market. And the market loved it.

Quick to capitalize on the Mach III’s success, in 1971, Kawasaki duly introduced a trio of triples focused on that bike’s two-stroke theme. First up for the new additions was a bigger and badder 750cc variant, the Kawasaki H2 Mach IV, followed by the 350cc S2 Mach II and finally the diminutive 250cc S1 Mach I, all sold as 1972 models. 

Not surprisingly, the 500cc and 750cc triples garnered the lion’s-share of attention from magazines and riders alike. And yet, the little 250cc and 350cc models, almost forgotten today, were stars in their own right — especially the 350 Mach II, which morphed into the 400cc S3. 

The Kawasaki S3 — the best of the bunch
While the 250 Mach I changed little in its production life, Kawasaki continuously developed the 350. In 1974, it became the Kawasaki S3 Mach 2, its engine enlarged by 50cc to 400cc and, most notably, rubber-mounted to a new, strengthened frame. The earlier 350 was already considered the best-handling of Kawi’s triples, and the new S3 was even better. "This is one Kawasaki that can be stuffed into a corner with lots of confidence," Cycle World said in its January 1974 issue. "It can be flicked from side to side, power on, except in the first two gears. In that situation you have to ease the power on to keep the front wheel down. If it had a little more power, production racing the 400 could be lucrative."

With 42hp it was no slouch, but like most two-strokes, its power tended to come in sharp peaks rather than broad waves. "The S3’s engine is sluggish at low revs," Cycle noted in its January 1974 review, "but when the tach needle moves past 5,500rpm those triple cylinders come to life in a large way." Even so, the bike’s power, smooth-shifting five-speed, compliant front end (which also generated criticism, with some testers complaining of a tendency to pogo on rough surfaces) and generally agreeable ergonomics made it a standout in the sub-500cc class.  

Our little triple
Kurt Limesand acquired his 1975 Kawasaki S3 Mach 2 when an office mate discovered Kurt’s affinity for old bikes. Her father had inherited the bike from his dad, the original owner, and had decided it was time to let it go. Thanks to a less-than-complete description, Kurt thought he was getting a KZ400, but figured he couldn’t go wrong for the $150 asking price.

Read Kurt Limesand's experience owning and riding his 1975 Kawasaki S3 Mach II 

What he got is the bike you see here, a clean, low-mileage survivor showing a paltry 2,925 miles when we picked it up. Other than a new set of tires, new chain, battery and some serious cleaning, the bike is as Kurt found it. It’s not perfect, but it’s not too far off, either. The paint is good, the instruments are clear, the seat is free of rips and the chrome – right down to the impossible-to-find exhaust system – is just about perfect. Did we mention he only paid $150 for it? 

Getting familiar with the 400, the first thing you notice is how small it isn’t. Its 30in seat height is only two inches lower than the 500cc Mach III, and its raised, wide handlebars pull back slightly for a comfortable, upright riding position. Instruments are simple, with a 140mph speedo to the left and a 12,000rpm tach to the right. On a panel between the two are the customary lights for turn signals, high beam and neutral, with the ignition key at the bottom. 

Turn signals are on the left cluster, which also houses the horn button, the choke knob and the high-low headlight switch, while the right cluster holds the on-off switch for the headlights and the three-way off-on-off switch for the ignition. You’ll note we didn’t mention a starter switch, and that’s because the S3 doesn’t have an electric starter, and was never offered with one. 

Fire in the hole(s)
Starting the Kawasaki S3 is a simple matter of fuel on, ignition on and full choke (holding the choke since it doesn’t lock in place), followed by a lazy swing of the kickstarter. You have to be in neutral, clutch out, as the engine doesn’t have primary kickstarting. Starting on our bike was rough at first, the engine sputtering and requiring a number of prods before it would finally agree to run, and then needing a good two or three minutes before it would idle on its own.

The cable-actuated clutch is smooth and light, and shifting down into first produces a barely audible "click." In our early rides, we found pulling away from a stop to be a trial, the engine immediately faltering unless we built the revs up over 2,500rpm, and even then the bike would bog heavily until we were in motion. At first, we thought something was wrong (something was – more on that later), but a period report in Cycle citing the S3 as "sluggish at low revs, but when the tach needle moves past 5,500rpm those triple cylinders come to life in a large way" had us thinking it was just the engine’s natural character. 

Shifting is excellent, and whether you’re going up or down a cog, the S3’s five-speed gearbox is just plain fun to row through. Once on the move, the S3 feels light, almost like a bicycle, and the ring-ding rasp from its exhaust sounds like a chainsaw on steroids. It’s a good thing all that noise is behind you, because if the mufflers outlets were any closer to the rider we think it would get pretty tiring, pretty fast. 

Handling is neutral, and the bike feels stable and calm, even in the mild crosswinds we experienced. It’s no canyon carver, but throw it into a corner and it responds with good feedback and no scary twitches. We thought the front suspension a little harsh, and the rear is definitely on the hard side. Curiously, we noted that the rear springs were wound tight even with no weight on the bike, a fact noted by testers back in the day. That means the springs are bound up before they’ve even started doing their job, severely limiting their capacity. 

On the road the S3 seemed happiest at 65-70mph, but quick blasts up to 85mph were no problem, as long as we wound the engine up a bit in fourth and then shifted into fifth. The back drum brake on our bike felt wooden, but the front disc gave excellent bite and was more than up to the job of hauling the S3 down from speed. The bike’s low, sub-350lb weight helps, of course. 

On the mend
The more we rode the Kawasaki S3, the more we became convinced something wasn’t right. While the engine has a reputation for being peaky, the performance of ours was getting ridiculous; unless you kept the revs over 6,000rpm, it was almost unrideable. Part of the Classic Experience is working through some routine maintenance, and we used that time to good effect here. In addition to normal stuff like checking the air filter (an easy, five-minute job), the spark plugs (ditto), oil injection pump setting (another five minutes) and adjusting the drive chain, we took a close look at the carbs and ignition timing.

We found that the no. 1 and no. 3 carbs were loose on their mounts, creating an air leak. We removed all three (a gratifyingly easy job, taking all of 15 minutes), inspected their floats, ensured the slide needles were all on the same setting and then snugged them back in place. After re-synching them and setting the base idle and fuel/air mixture, the bike ran much better, starting on the first kick and taking only a minute or so to warm to idle. 

It still bogged heavily, however, so we turned our attention to the ignition points, and there we found our biggest problem: The gap on all three – yes, three – sets of points had slipped from a prescribed setting of 0.014in to as little as 0.003in, throwing the bike’s ignition timing completely off-kilter. After cleaning the points and setting them to spec, the transformation of our S3 was nothing short of amazing. 

Simply put, it was a different bike. Suddenly, it would pull strongly and cleanly almost from idle, and top-end performance, which had been the bike’s only redeeming feature, jumped by leaps and bounds, with a strong surge in power at 5,000rpm. First and second gear wheelies were suddenly easy, and a quick run saw an indicated 100mph without really trying hard. Fuel mileage, which had been coming in at a dismal 22mpg, jumped to 33mpg. Definitely still poor mileage, but a 33 percent improvement, nonetheless. 

Not surprisingly, we found ourselves wanting to keep the bike a little longer: "Sorry to see it go," we wrote in our last notes. "It’s been a blast to ride. It’s light, agile, and now that it’s running correctly, very easy to ride, tractable even in town and with plenty of power out on the road." No, it’s not a touring bike, and while it’s amply fast, it’s hardly the fastest thing on two wheels. It’s a little too small for highway duty, and a little too peaky for slow-speed crawling. But it’s perfect out on a two-lane blacktop, and it’ll make you smile every time you twist your right wrist and roll on the power. Just don’t forget to check the gas. Oh, and the oil. 

Restorer's View
Z1 Enterprises
Marion, N.Y.
(315) 926-5054

Thanks to Kawasaki basically abandoning Kawasaki S3 parts support after it went out of production, parts are hard to find. 

Because of the parts situation, Z1’s Jeff Saunders says that restoring an S3 can be difficult. "We’ve struggled to find parts for these bikes. There are not a lot of aftermarket parts, so you’re searching out NOS (new-old-stock) parts or used parts — and even some of the simple things aren’t cheap." 

That means potential buyers should have their eyes open, Jeff says. "They’re good bikes, the issue is when you get one the cost of rebuilding them is really quite high. If you’ve got crank seals to replace, it’s beyond most people’s capability to pull a crank apart. You can kill $1,000 very quickly, but the bikes haven’t appreciated enough to merit doing it." 

Mileage is key: "If it’s got over 24,000 miles on it, it’s time for a rebuild. Look for a nice, low-mileage bike; under 10,000 miles. And look for frame issues. Because they were wheelie machines you get a lot of stress problems where the frame came down too heavy too many times. Look at the gusseting for damage; you can get a twisting of the steering head." 

Jeff cautions owners to make sure the oil pump’s working properly. "A lot of people disconnect it and go with mixed fuel. The problem with that is it’s not giving adjusted metering with engine speed, so there’s a tendency to foul plugs more. 

"They’re fun to ride: When a two-stroke kicks in it’s quite an adrenaline rush. They have lots of appeal, they have that interesting unbalanced look for the pipes — and I think they have the potential to climb up in value. As you look at some of these bikes in the second tier, bikes like this fit in there. They’re somewhat collectable, but they haven’t started to appreciate in value yet. Like muscle cars, a lot of the vehicles that were looked at back in the day with disdain are bringing a lot of money." MC

Sample Parts Prices

Z1 Enterprises 
- Carb rebuild kit: $17.50/three required
- Points and condenser kit: $36.27
- Steering head bearings: $44.86/set
- Front brake pads: $26

- Oil change (transmission):
- Every three months or 2,000 miles
- Air filter, spark plugs, points and timing, oil pump:
- Clean, adjust or replace every 2,000 miles

Clubs and information 
Kawasaki Triples Worldwide

Parts and services

Bike Bandit 
Z1 Enterprises 

Read more about the bikes mentioned in this article: 
1970 Kawasaki H1 Mach III 
Kawasaki H2 Mach IV