Retrospective: 1967-1971 Kawasaki A7SS Avenger 350

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Kawasaki was the last of the Big Four Japanese OEMs to enter the U.S. market, setting up shop in greater Los Angeles in 1966 with a couple of tiddlers, an old-fashioned British-style OHV 650cc parallel twin and a very nice 125cc two-stroke single identified rather unromantically as the B8. The Kawasaki marketing boys (don’t know if any girls were involved) soon came to appreciate the use of a catchy name, and when the 250cc two-stroke twin, the A1, went on the market that year, it was called the Samurai—a brilliant choice. And a brilliant motorcycle, with rotary valves, a new concept on the street.

Realizing that the go-fast part of the motorcycle world was quite profitable, Kawasaki upped the ante, or we could say “cylinder capacity,” within a year, and did it with a vengeance—or maybe avenge-ance. When the 350cc Avenger two-stroke twins, the low-pipe A7 and high pipe A7SS (Street Scrambler) got to the American market in 1967, everybody was impressed.

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Despite lighthearted denials from the company, the 350 (bore 62mm, stroke 56mm = 338cc) was essentially a bored-out version of the 250, but with significant improvements. The Avenger engine was like the Samurai’s, a rotary disc-valve twin, with valves operating off both ends of the crankshaft. Instead of the 250’s 22mm carburetors, the 350 had two 26mm Mikuni MV carbs sticking out the sides—best not to lay this baby down at speed. End to end, the engine was almost a foot and a half wide. Four main ball bearings supported the crankshaft and provided a sound seal between the pistons. The primary gears spun the generator that was mounted inside the air-intake casting behind the cylinders, which kept a cool flow running over the AC unit. The generator also served to fire the points in a very reliable manner, better than being at the far end of a slightly wandering crankshaft. Capacity discharge ignition was added in 1969.

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Lubrication was improved, the 250 merely mixing oil with the gas at the intake ports, while the 350’s new Injectolube system metered oil going directly to the intake ports and added direct oiling, under pressure, to all the bearings and rod connections along the crankshaft. The “control cable,” as it was called, ran from the throttle to the two carbs, and a third line went to the oil pump.

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The new oiling system had a direct correlation to the factory-advertised power, which went up some 30 percent, from 31 horses on the 250 to 40.5 on the 350. This was good for a quarter-mile time of less than 15 seconds and a top speed of more than 100 mph. In best advertising fashion, the ads exaggerated a bit, claiming a quarter-mile time of 13.8 seconds and a top speed of 115 mph—though no magazine tester could equal those numbers. Maybe a 90-pound rider with a strong tailwind had achieved it. Max power came out at 7,500 rpm, but since there were no valves to bend, misguided enthusiasts would easily run it to 9,000. All this from a stock 350 costing a reasonable $850…buyers had no complaints.

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Power went through a wet clutch and five gears—with neutral at the very bottom. The gearbox had its own separate oil supply, and a change was recommended every 1,800 miles. Another bit of two-stroke maintenance was to take the heads off at that same mileage and scrape off the built-up carbon with a wire brush. Do the top of the pistons, too. And don’t forget to take the baffles out of the exhaust pipes and clean those, too. Two-strokes had a lot of emissions, which is why the EPA later banned them.

The steel frame, a weighty but justifiably strong piece, was tubular, the cradle running wide as it went under the engine and reinforced by cross braces where needed. Kawasaki seemed to have found a reasonable balance between around-town and racer-road when it came to handling, with the motor being firmly gripped. Up front, the telescopic fork provided adequate spring rates and damping, with rubber boots covering the chromed sliders. The SS had both a friction damper and a little hydraulic rod to control any untoward movement. At the back, chromed shock springs were left uncovered, always an eye-catcher, with three-way adjustability. Eighteen-inch wheels were fore and aft, with a 3.25 tire at the front, 3.50 at the back. A double-leading shoe brake did a good job on the front wheel, with a single-cammer at the back.

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Between the axles was a rather short 51 inches, all the better to flick through those tight curves. And the curb weight, with five pints of oil and 3.5 gallons of gas, was a respectable 340 pounds.

The look of the SS was one to catch the eye. The public loved those upswept exhausts, with perforated heat shields offering protection to the rider and passenger, chromed fenders (the rear one slightly bobbed to enhance the sporty look), chromed panels on the gas tank, chromed exhaust and well-done paint on the tank, side covers and headlight nacelle. A nice, flat saddle could easily hold two people.

The nicest aspect of the Avenger was that with a flexible engine, the rotary design gave a much wider usable range of power as compared to a piston-port engine. The rider could drop the revs down to 2,000 rpm and have a pleasant, quiet ride through town. While out on the back roads those two pistons would create a real screamer at 7,000 or more rpm. Not many of us can remember the sound of a two-stroke twin at full rip, but it is impressive.

18 COMMENTS

  1. Two weeks after buying a brand new 250 Samurai in ’67 for $695 I traded it in on a new 350 Avenger (a whopping $100 more). The dealer chopped the rotary valves before delivery and that little 350 would beat my brother’s 900 Sportster and the neighbor’s 650 Bonneville – any way they wanted to race. It was an amazing bike; put Kawasaki on the map here in the States. You had to put all your weight on the front end, launch hard while slipping the clutch, and it’d smoke like crazy at full throttle, but with the howl of those dual carbs that bike would flat out get it. Everyone raved about the RD350 Yamahas but the Avenger would beat them every time. In ’69 the Mach III came out and the 350 became yesterday’s news but I have fond memories of that chrome tank little 350 (and its baby brother).

    • Dave, I was one of ‘those’ R5 Yammy boys. Not long after buying, a guy jumps a median to challenge me to a “duel”. I respectfully declined a drag race,but asked if he would like to follow me through some twistys.
      He ‘wisely’ said no, and for some reason, never did encounter him again!
      That was 1971. Many years later, I bought a non running ’68 Avenger (2012), tore it apart and cleaned every nook,etc. I was much impressed with the quality of almost every piece I handled. It seemed no heavier than the Yamaha,yet was built to a higher standard.
      Unfortunately, in a poor state of finances and mind, I sold it to a guy in Minnesota. Shoulda hung onto….
      What a screamer! And I’ve ridden H-1s, etc. Cheers.

  2. Bought one of these in 1970 right out of high school (1967 model). The original owner was wanting a Mach III and gave me a deal. Was quite a step up from my little Honda 50! It was a screamer with expansion pipes on it, but VERY loud, only used those on rare occasions. Replaced the seat with a shorter café racer type seat, made a world of difference in the looks. Loved that bike, my first “big” ride.

  3. For my 16th birthday instead of a car, I got a 1971 Kawasaki 350 A7. What a rocket ship! Beat all the 350’s out there and a lot of 650 twins. But this doesn’t come without a price, the bike spent many days at the dealer for warranty repairs. The 2nd day I had the bike, it seized up, dealer didn’t prime the oiling system correctly, 6 months later crank goes out. Just out of warranty, rotary valve seal fails, sucks the oil out of transmission, stuck in 1st gear. Despite all the problems with this bike, it was simply a fast great handling motorcycle. I wish I still had it today.

  4. Kind of an incomplete history of the A-7. While the original one (1967-68) had 26mm carbs, points ignition and a claimed 40.5 bhp, the 1969s not only got CDI, but they also got 28mm carbs (with rotary valve covers to match) and exhaust pipes with internal changes which bumped power up to a claimed 42 bhp. The 1969-71s were the really fast ones…when the CDI was working…or they weren’t suffering seizures due to rushed break-in periods (see Cycle magazine’s 1970 350 comparison test). Those were likely as fast, if not faster, than the RD-350s, despite the RD’s 6-speed box. The only real competition that the 1967-68 A-7s had was the 6-spd Bridgestone GTR. I, unfortunately, purchased a 1971 Yamaha R-5. An over-rated pile if there ever was one.

  5. I bought my A7SS while in the service in San Diego. Still in my mind the BEST handling bike I’ve ever had. Always used synthetic oil and maintained it well. I had a problem with the Capacitive Discharge Ignition System. I replaced that several times. If I had one now I would have it as a spare part all the time. I rode this bike hard 50K miles up and down the West Coast during the three years I owned it. I still tell many stories that we had. I met my wife on it (47 years ago as of 2018). She drove us off a wash. The forks bent back touching the exhaust. Before we went off the 12 foot deep wash I threw her over my shoulders. She ended up on the road (like the captain) I went down with the bike. The only way I could get even with her was to get married. She’s been paying for 47 years now. Ha – ha – ha.

  6. Freddie, if your still out there…
    If it only runs correctly in exceptionally cold weather, you might look to fuel mixture, sounds like it’s running very rich, perhaps the float level is set incorrectly? There could be several other problems, but checking the air cleaners for blockage, the carbs for correct settings, ignition timing and make sure the exhaust baffles are clean.

    Hope this helps, if anyone even looks here…!!

  7. Love Clement’s articles on vintage bikes. A good friend of mine bought a new ’69 A7 in early ’69. Traded his Bridgestone 175 in on it. It was fast enough at that time to be a serious competitor to larger displacement bikes. I recall that he had some work done to the rotary valves and maybe some other mods. By summer he started racing at a local major dragstrip. On the first Sat. night he took top bike and took a large trophy instead of cash. He took top bike every week after that for most of the summer. $100 prizes, which was a significant amount of money then. It was all street ridden bikes back then. He consistently got his ET’s down from the high 13’s in the beginning. He eventually ran a very low 13 time. ( I saw the time slip) then quit drag racing.

  8. I bought a New 1967 A7 Avenger 350 in January 1968. I was in the Air Force stationed in Nebraska at a radar station. The owner of the bike shop was a member of a local bike club. I was invited to join. I was the only Jap bike in the club. All the menbers rode Harleys, BSAs, Triumps. They made a few remarks about my bike not being American. May be first time I heard the term “Rice Burner”. Well after they all rode the 350 the remarks stopped. That thing was a rocket. I only got to enjoy it for 4 months. I received orders for Viet Nam and I sold the bike to a club member. A Harley guy!

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