Hmm...lots of ideas here!
Honda made the 750 engine much like their Honda 160/250/305 (as far as servicing is concerned) for several very important reasons:
1. They were sorely worried that no 'average' Honda mechanic would be able to work on it, so they wanted it to 'feel' familiar, and use similar tools, with the existing Honda lineup. This was a large portion of their design 'philosophy' for the whole bike. They were EXTREMELY afraid of a very public failure, once the bike got into customer's hands' if the shops could not take good care of the customer and the bike.
2. Honda was not a big company at the time. They used those things they knew, combined with some of their racing expertise, and same-O, same-O part designs that they could easily make with their tooling and casting facilities. That's where the wiring came from, too: on the K0/K1 bikes they even used the [undersized] 2.5mm bullet connectors in many places.
3. Honda wanted to beat all the competition, not only in pizazz (4 cylinders!) but in HP (67, where the new BSA Rocket 3 was 66 HP), increased stopping power (disc) that should NEVER rust (so, it became stainless, which doesn't stop as well), large instruments that could be easily seen at arm's length (in the dark, too!), which NO ONE ELSE HAD at that time, and all for a price of $1295 delivered. Of course, this price quickly went to $1495 by the Fall of 1969, then to $1750 by the summer of 1970, but who's counting...the average American in those days made about $100 per week. The Rocket 3 cost well over $2000 in those same dollars.
4. The bike had enormous speed potential (it was the fastest PRODUCTION bike in the world, and the quickest STOCK factory bike until the Kawi Z1 appeared) and distance ability, so the seat had to live up to the long ride. It was immediately dubbed the SuperSaddle by Cycle mag, and I completely agree: in that era, most bikes felt like you were riding on a board. I threw a leg and rode over 1000 miles in a single day after I had mine just 2 months, and never looked back.
5. The bike came in Candy Colors! No bikes came that way then, only custom bikes looked like that.
6. It had an oil filter! Only the BMW had one in those days, but you had to be a special person (I'll leave it at that) to ride a 1969 BMW.
7. It had a headlight that was good to 90 MPH in the dark, and it was HUGE by bike standards. The taillight, straight from the CB350, not so much...that didn't get fixed until the K2.
Things it did not have:
1. Nimbleness. It was 540 lbs, had plastic swingarm bushings, soft ball races in the headstock, and undersized tires for the speed, weight, and power of the bike. It FORCED tire makers, notably Bridgestone first and Continental later, to make tires for bikes that really meant something. Once Avon got into it, the tech became what we now enjoy (or gripe about...), to the better of all bikes. The rest of that, after 1971, is history - good history.
2. Long-lasting ignition, to match the bike's enormous [new] mileage capability. Hitachi and Tokyo Electric Corporation (TEC) came to Honda's rescue with points and condensors that set the stage for the next 15 years of motorcycling. When 'electronic ignition' came about in force in the early 1980s, it wasn't until TEC got into it again in 1990 before it became 'good' equipment.
3. Wheelbase. It was (and still is) the shortest 750cc bike around. Early prototypes had longer swingarms, but poorer handling (dang those bushings!), and the longer chain drive was snatchy and noisy - and gooey! So, it got shorter. The K0 had 98 links and too-small sprockets, which wore the chain in record time (4k miles, typically) with nasty results. Diamond Chain rescued Honda here (after Honda bought them, with AMF/Harley, in 1971) with their patented XD chain tech.
What it spawned:
1. An entire industry of aftermarket products for bikes. Those of us who didn't live then don't realize that there were NO luggage racks, optional seats, fairings, saddlebags, riding gear (except black leathers), wet-weather equipment, heated [anything] like vests, gloves, boots, etc., rear-mounted footpegs, floorboards, optional electronics, optional ANYTHING: it ALL came about because of the CB750 and the race by other Japanese bike companies to compete with it.
2. In just one year, it completely changed the American perspective on "who a motorcyclist is". By 1970, bankers, lawyers, store owners, and college kids were riding these beauties everywhere, and people would actually stop to look when they saw one. We no longer were black-clothed, greasy hoodlums, but now might be your neighbor.
3. Motorcycle Safety Training, in dozens of forms, became VOLUNTARILY popular by 1971 as more and more folks wanted to ride 'across the country' on a Honda. I personally both benefited and taught at several of these operations, even created one myself from our shop.
And...the CB750, more than any other thing, put me through college and landed me in Colorado, cash-flush, in the peak of its popularity.
Cool stuff.
