The H1 500 was the first triple produced by Kawasaki, and went on sale in 1968. Kawasaki realised that there was a market for such a different machine in the most popular 'classes'.
So the S1250 was born in 1971 a inline three producing 32 bhp @ 8000rpm, giving a top speed of 104mph and a s q of 14.7 secs, now of course these are Kawasaki quoted figures, so takw with a pinch of salt! In 1976 the S1 became a KH 250 and lost a little power, carried on in production until 1980, when it was eclipsed by the Suzuki GT250X7.
In 1971 the S2 350 was also marketed, with allegedly superb handling (for its day) and claimed to be the most powerful 350 production bike, putting out 45 BHP, and boasting a s q of 13.6 secs and a top speed of 112MPH. Produced until 1973 when it had the capacity increased to 400 and became the S3, which in turn became the KH400 in 1976 and produced untill 1980, power was down compared to the 350, and the 400 engine is quite different to both the 250 and 400 in power delivery, quite a low revving engine, peaking much lower in the rev range.
I'll update this with pictures of all the different models, frame numbers etc when I get them, if you can help mail me please!