Anyone who has THE answer to this question, please write in !
Chris and i have bantered this one back and forth a few times.
IF acorn hex head 6mm screws were ever used on a production CB750, to my way of thinking they would have to have been fitted on the very first 3 or 4 or 5 machines off the line, perhaps before the assembly line went into full swing.
If i recall correctly from VMD, Andy Dixon's #175 has acorn head *NUTS* with 6mm studs in the case holes, protruding through the starter cover. The parts books shows screws, not nuts, but then who am i to say what came on a bike as original.
The picture in the early parts book showing 1. these acorn head hex screws is no more confounding than the 2. winged nut shown in same book to lock the upper portion of the throttle cable in place or the 3. headlight ears showing welded straps to route cables or the 4. exhaust manifold spigots having relief on each side of the plate.
No one has shared seeing a production CB750 fitted with any of the forementioned parts. I'm not saying, no one has seen these parts. What i am saying, no one has yet shared their seeing these parts. I believe these parts exist and were quite possibly used on the first few, probably single digit, bikes built at the factory.
We KNOW acorn head hex screws were fitted on the Late Pre-Prod bikes to fix the starter cover to crankcase, we KNOW the same for the exh.spigots with relief and we KNOW the same for the headlight ears with welded on straps.
From what i remember Bob Jameson sharing with us, the #1 Prod.750 was assembled on the floor, by a group of engineers, not on the assembly line. It is not unfair to reason, the next few single digit bikes could have been used for testing, shows, industry principals and not for retail sale. It's possible these very first few machines could also have been built on the floor and not on the assembly line. It's also possible the parts being used to build these very early bikes were the very earliest of "one-off" items (brake lines/oil lines, etc) and were not taken from bins full of said parts used to supply an assembly line in full operation.
In fact, we know the frame carrying E24 did not have acorn nuts, was used for road testing and this engine was documented by the road tester for Motor Cycle World, March 1970. It's safe to say this bike was not intended for retail sale at the dealer level and probably some lucky industry insider took ownership of the bike. This machine is pictured on the cover of our website. From what my research of my extensive literature collections allows, the American press was given at least two producton bikes for testing. A red (Cycle World Aug.69) and a blue-green (Modern Cycle, Oct.69) machine.
The tester riding blue-green E24, in the March 1970 Motor Cycle World issue, notes their magazine had to wait for the machine, because other magazines were testing the bike prior and the machine when they received it, the auto chain oiler had been turned off due to making a mess on #'s 1-2 exhaust and the machine had 5200 miles on it when they finished testing.
Anyway..... i have looked with a magnifying glass at many pictures in the some 30+ odd magazines and numerous pieces of factory literature i have from the era and on not one machine have i noted the acorn nuts, throttle cable wing screw, radiused manifold spigots or healdlight ears with welded straps.
So, i will venture, again, if the acorn head hex screws were fitted, it would have been to only the very few early prod.vins, most likely single digit machines.
I have a set of these acorn head screws from Yamiya fitted to 232, only because i like 'em. I almost fitted the radiused manifold spigots from Yamiya and decided at the last minute to not do so, because evidence is overwhelming on other existing machines in this vin range, they do not have these radiused spigots.
Steven, i need clarification on your question, "I know chromed starter cover bolts were used at some point on the production run of Sandcasts/K0's but when?"
Are you questioning if Honda fitted, earlier in the production run, standard hex head 6mm screws, not chromed, i.e., plain head zinc plated screws or "8" hex head zinc plated screws ? And then later in prod.run, began fitting chrome std.hex head screws ?
Or, is your question referring to when these chromed standard hex head screws were fitted in contrast to the chromed acorn hex head 6mm screws ?
WOULD ANYONE WHO HAS SEEN THESE RARE PARTS ON EARLY PRODUCTION VINS, PLEASE WRITE IN ?
