Along about this same time, Bridgestone had developed an air cooled prototype inline 3 cylinder rotary valve engine and bike, electronics behind the cylinders, in the V between flywheel and trans housings, under the 3 rotary valves set up like a later model Can-Am two stroke. I actually saw one of those bikes at Chiba, Japan, in the shop at Bridgestone while I was on leave. A friend of mine was on the development team that built it. It had a inlet port cavity in between the center and left cylinders, and a two piece rotary valve for the center cylinder that clamped to the crankshaft. All 3 carburetors were inline, like the H series, behind the rotary valve intake tracts, behind the cylinders. Reports were it was faster than all get out, but was fitted with Suzuki style double panel 4 leading shoe front brakes, and typical of the day death wish frame and suspension, totally death defying.
Then, there was the super secret "H3" 750 4 cylinder two stroke. In very early 1973, only 4 of us from Team Kawasaki Road Racing, and 3 from Research & Development saw this bike, for ONE day only at Ontario in a closed session. This bike was the most likely candidate to replace the H2, in 1975, but never got built. It was designed by a very capable Japanese engineer, whom got a bit irritated when Kawasaki told him they didn't want, nor need liquid cooling on their street bikes, too heavy, too complicated. The engine had 4 cylinders, 4 rotary valves, arranged in a square design, 6 speeds, and was literally (mostly, when the front wheel was still in contact with the ground), a full-on, land based ballistic missile of the time. The engineer quit KHI and moved on.....to Suzuki, later designing and developing what we came to know as the RG500 Square 4.
The twin rotary valve 500 was mundane, looked like a combination of an A7 and T500. Ran well, but, not snazzy enough.
The "L" engine, well.......................
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