I recieved a mail from Mr. Dan V clearing a lot of history about the origins of Kawasaki and The Big K making it big with the Machs. He has made the post so clear that I just copy pasted whatever he wrote. Although he didn't mention to which post he actually referred, but I believe its a post for Kawasaki in general. So far I have put 8 tags for Kawasaki and this post more so applies to this thread.
First of all, I was there. I owned the bikes mentioned and would like you to know their correct history. The A-1 was the Samurai 250cc, with rotary disc valves between the side mounted carbs and the engine case. The A7 was the Avenger 350cc (nominal, actually 338, but this was better than the punched out Suzuki 250 X-6 Hustler 350's 315cc). The A1 and A7 also came in the then fashionable lowered geared, skid plated, braced handlebar, high piped versions with the SS suffix, A1SS and A7SS. The A7SS was also sold as an American Eagle 350 with advertisements featuring Parnelli Jones. The design of the 500 as a punched out 350 could not have been considered because of the rotary valves' requisite side mounted carbs. The center cylinder would have had to be fed from the back of the engine, even if such a weird design as a two rotary, one piston or (later) reed port engine had been considered. For the record, the different 500s were as follows: White with blue 1969, black with grey 1970 and red with white 1970. These bikes were identical and quicker than later models and had a bridge in the middle of the intake port . I felt that this diverted airflow for better breathing and cylinder fill. Early models, white 1969s and black 1970s, had the spark plug wires running below the carbs with a different ignition cover (flat on top), that was updated to keep the wires out of the water that collected below the carbs. It has been decades since I have seen an original flat cover; the update was necessary to ride in the rain. The Blue 1971 and Peachy 1972 had the bridge machined off the intake port and too much stuffing in the exhaust pipes. In 1972 you could get a disc brake but not with the electronic ignition. It was either/or, not both. I know; I tried. Points suck. From 1973 until the end, the bikes were much more reliable and better looking, but were slowed down in enough ways that I never owned one. Mach IV and KH500s (so called after 1972), also had much better ignitions with modern electronics and no mechanical distributer, as well as a front disc brake. All of these had the now famous Kawasaki tail section behind the seat as well a a longer swingarm.ON ROTARY VALVES: The thought of the day was that a big advantage of the rotary valves was pre-programmed port timing, varied by using different discs. Additionally, the disc closed the intake at any place you designed into the shape and opened it likewise, thus much less blow by/through of the fuel through the cylinder and blow back through the carb under compression. It turned out that the intakes from the carbs being on the crankcase was as important as the disc, therefore predating the later crankcase reed induction for efficiency. Suzuki used two forward cylinders and two rear cylinders (Square four) with rotary valves to win seven consecutive 500 GP titles, until Yamaha figured out how to partially regulate the exhaust ports with adjustable height exhaust valves (powervalves), which still allowed an inline engine. This was quickly added to the Suzuki square four as well as a later Yamaha square four 500, Kawasaki square four rotary valve 500, and Armstrong 750 square four raced as a Buell at Daytona by the "Genius Eric Buell", who according to Harley-Davidson, made the bike from parts machined in his garage. (He did machine the footpeg and handlebar mounts to the bike that had dominated British road racing for a few years before he brought it to the USA.)
Later, V motors were tried with a common valve for left and right pairs of cylinders, like the Seadoo Twins. Of course Aprilia still wins 250 cc and 125 cc world championships with (half square) rotary valve engines. But I digress. I did try reed valves on an H-2 with outrageous results in the midrange on fully ported H2-R cylinders. We did not have the capability of doing powervalve machine work, but I have heard that is was done in England with great results. Today, the 750cc world record for speed through the quarter mile is held by a Mach IV powered dragbike, 177 mph. This bike still races. When I was talked into getting my first four stroke (Z-1, of course), I kept my race prepped 1969 Mach III. It was much more fun and sounded too wicked to be true. I now ride a 500 Suzuki Gamma with 123 rear wheel horsepower and a Mach IV. I wish The Kaw 500 Racer that Eddie Lawson raced had been streetable but Suzukis are good, too. They were just missing a cylinder on their air cooled engine and were buffaloed by weight and by Daytona speedway tech idiots on their 750. I do ride good handling bikes in the mountains, but have about as much fun riding crazy sounding "junk" when terrorizing the kids and "Bikers".
Two stroke spray is revenge.ADVICE: In the mountains, stay away from moving chicanes, i.e. Harleys and cruisers. Sportbikes don't kill, moving chicanes kill.Cheers! DanV
Dear Mr. Dan, Thank you for your mail. From the pic provided in the website, it seems you must be around 45-50. I am in my 30s and as such during the time mentioned, I was not even born. For me, its just a passion to learn more about bikes and the net is really a wonderful media to learn and exchange views. THANK YOU for sharing your experience and clearing a lot of errors. I hope you understand in no way I would like to tarnish the image of the Big K or for the matter any other brand. Its just a lack of knowledge on my part.
I would also request other readers to clarify me wherever applicable which will give us, passionate bikers a lot to learn from people who have lived through the experience of riding and owning classics.