Honda CB750 Sandcast

Frame & Engine Number Spread

kp · 20 · 2763

kp

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The topic (or debate) of frame/engine number spread is an interesting one. Owning Frame 28 with Engine 132, I often see comment questioning (incorrectly I might add) this number spread. Frames 7 came with engine 90, 9 came with engine 97, 123 came with engine 247, 175 with engine 263 and 180 with engine 302. So go figure. Rarely a comment is made (if comments there are) where a 100 or higher difference occurs with a 3 digit or higher frame number.  Surprisingly, I've seen comments (comments there has been) made by some when a frame/engine number is considered too close. Other discussion is had on engine numbers being lower than frame numbers where some believe (believers there are) this should not occur at all. Honestly, I have no idea why some number spreads are very close and why some are very widely spaced, why some engine numbers are lower than the frame number and we could speculate these questions for the next 100 years and still have no answer (for answers there isn't). On thing we do know factually 100%, is that the pairing of frame and engine was a random production line event (and this ultimately could be the factual 100% answer or the golden fleece itself) Of the pairings we do know about, many are within a spread of 100 and most generally are spread to an upper limit of 200
Some interesting data is available in our own VIN directory, however this does not prove anything factually about frame engine spread. These observations (Indeed! I stole this little saying from Mr Swan  ;D ) merely show the diversity of frame/engine number spread using the VIN registry as a guide (for a guide it is).
Of all the registrations recorded, approximately 75 or so have a difference of 300 or more, and of those, approximtely 53 or so have a difference of 400 or more. We can say without doubt a proportion of these are engine/frame swaps, however not all. Regardless, that's a significant number of machines with a wide spread given the number of registrations in the directory. And we must equally accept (accept we must  :)) there will be a fair number of frame/engine swap machines in our directory with a spread of under 300, as owners wanting to make whole their "not complete" machine spread to within what most consider the norm, let's say not more than a 250 difference. You still here?  ;)
But wait - there's more  8)
Of the 27 pairings of the first 200 machines registered the following is noted:
13  (~50%) have a frame engine spread of over 30
7  (~25%) have an engine spread greater than 80
3 (~12%) have a spread of over 100
Now there's a bit of stuff for Ya'All to consider
Gin & tonic time I think (for thinking I sometimes do)
later
KP
 
Yabba Dabba KP


kp

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Further to the above post we have 75 pairings over the 300 spread. I'm tired and half way through my second G & T so what does that represent percentage wise of all our paired registrations. No counting single frame without engine and vice versa registrations Would 10% be too high. Of those 75 I didn't count frames with die cast engines or blank cases without a number.
I know of at least 1/2 dozen registered combinations where an engine was paired with a frame and the spread was below 200. In my own case, many years ago, I swapped out an engine to a frame so the spread was closer. I'm thinking that the frame and engine were original pairings as I was told that on purchase, but the spread was around 460 and I didn't accept it to be a correct pairing. Oh what we have learnt many years on.
Yabba Dabba KP


DW69K0

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Good stuff KP!

I have always held the belief that frames are easy  and predictable to manufacture, not many moving components. Engines assemblies have hundreds of moving components supplied by different vendors, many things can go wrong.

Thinking more engines were built and needed repairs than frames.

Honda CB750 K3 have some of the widest Frame/Engine spreads, some in the 1,000 (maybe off topic), but sure is interesting to note.


Sam

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Thanks for this research KP! This is just about what I have observed as well. Early vins have a tight spread, while later vins have a larger spread. It makes sense...Honda didnt build bikes in the first month as quickly as they did towards the end of sandcast production.

I do think there are valid examples of larger-than-normal spreads that are original. Honda was racing to get bikes out the door and clearly didnt care if the numbers were close together. If an engine had to be pulled from the line, fixed in some way and then returned to the line a day or two later, that was fine with Honda. They certainly wouldn't hold a frame for it while the engine issue was being addressed!
Ujeni Motors
Sandcast #410
Sandcast #538 Watch the restoration!
Sandcast #6592 All original daily driver.
Diecast #16608


kp

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Finally some discussion on the Board
Yep Sam, there won't be much of large number spread with early frames agreed, however we don't have a large enough pool to make any valid overall assessments. For the early numbers there are significant spreads relative to early production numbers. One thing though, the largest grouping of spreads is in the 3000 to end of 4000 range at ~37. The least is the 5000, 6000 and remaining 7000 range with only 16, whereas 1000 to 3000 is 19. This diversity is not seen specifically in the higher frame number groupings from my observations, in fact 1000 to 4000 has the lions share. Again the pool is too small to draw any valid conclusions.
Sam, I'm not so sure production was slow to kick off. Maybe the first week but looking at the engine case date codes referred to by Duane, seems that production was more or less equally spaced from late April until sandcast production end. The main issue with early production was engine case casting, not assembly or other component manufacture. I don't follow the history of assembly or assembly line locations as well as others, but I knowl that production really kicked off after the diecast engines began with twice the number of diecast to sandcast machines being produced in 3 months as opposed to 6 with sandcasts in the 1969 year. Chris Rushton may have more to offer
I personally cannot accept that there are no valid examples of larger than normal spreads and I'm not sure why anyone has this view. There are many valid examples. I have 2 such examples in my garage and of another I owned was also an odd spread machine, Allan Landry's machine is well documented, Duane Wilson has a machine I believe, Bo has a low frame odd one, there are several later 3 digit machines here in Australia, and more I believe spread around the world. A pairing is certainly not a pairing on the assembly line, rather they become pairings when machines literally roll out the door and are officially recorded. We know nothing about what frames and what engines were installed on the assembly line, or whether/or how many engines were pulled from frames, and if so at what rate. This can only be speculation. Nevertheless, the original pairing is what is recorded, and an official Honda register does exist somewhere and this has to surface (hopefully) sometime. Wow, won't that be an embarrassment to a few  ;D
Anyway, owners, members and followers will have their opinions and anything I believe, is, as always, open to debate
Later
Yabba Dabba KP


DW69K0

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Sending these photos as a reminder to how the factory was operating in 1969., as frames and engines are paired.
Credit to Tom Courtney-!

I always wonder how many are sitting around in other staging places before final assembly.


DW69K0

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I am in agreement with KP, from the limited data we have available, frames and engines in the 3,000-4,000 ranges seem to have the largest spreads in some pairing. Mid-June to July production. Data is still very limited.

3,000-4,000 Frame/ Engine range is where you will see mixed thin lip and thick lip clutch covers installed and oil lines changed from smooth ferrules to deeper crimped connections. The Frame mounting of the horn changed to the right side in this production period.

Best,
DW


Sam

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I agree with KP as well...I do think there are large spreads here and there.

I would be surprised if Honda was producing engines in the beginning of sandcast production at the same speed as towards the end of sandcast production. I suppose its possible, but, even now, manufacturing almost always ramps up speed as issues are worked out. Again, its possible!
Ujeni Motors
Sandcast #410
Sandcast #538 Watch the restoration!
Sandcast #6592 All original daily driver.
Diecast #16608


kp

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I'm not really knowledgable in the area of assembly but would seem the production of engines, and I guess other components, commenced around a month or longer before actual production. Bikes 1, 2 and maybe 3, 4 were I believe, assembled some time before main production. I've tried to establish the timelines from people I visit when in Japan but just cannot get any definitive answers. Many of the crew were experienced from other production lines and the training was undertaken with these first 4 bikes is my belief. They don't show up anywhere in publications or documentation other than 1 and 2 in the handbook and workshop manuals. I'm hoping to find out before one day. I just cannot fathom why no history is available with such an important motorcycle
Kawasaki can tell you where each bike went, including country and who for the first 20 or so. The bikes early history is well documented.
Yabba Dabba KP


Steve Swan

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elsewhere in this forum or website are pics Bob Jameson took of #1 being assembled as well as the picture taken March 15, 1969 of #1 with snow in the foreground and a group of men standing behind #1.   I remember at the 40th Anniversary meet i put together, Bob distinctly saying the men who assembled #1 were engineers responsible for designing the different parts of the bike and that these are the men in those pictures and are the same men in the March 15, 1969 picture.  i believe the 10 videos of Bob J's presentation are still somewhere on this site and may still be on YouTube, certainly worth watching  and re-watching especially for those of you not fortunate enough to be in attendance.  if you have not seen/listened to those videos, Bob gives many interesting details about production and testing.  Chris and Tom were at the 40th, i'm certain they have memories they can share being in the presence of Bob Jameson and Bob Hansen.


DW69K0

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Steve,
Digging through the threads, I cannot find a working link to the Ray Bayless DVD covering the 2009 AMA VMD.
Do you know if copies of the DVDs are still available somewhere?
Thanks much,
Duane




Don R

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 My 5511 has a nearly 400 number spread, a friend bought a sandcast two frame numbers different from mine and his also has the same approx. spread.


the-oz-slider

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hi ya'all, Ive been out of the loop for a while as I sunk my inheritance into CBX's and lost my mind when a couple of those proved to be well above my skillset to fix/ get running properly...... so I engaged the great and famous Graeme Crosby and his mechanic Tony to fix my problems and all is well, albeit my wallet now has mouse-sized holes in it you could throw a CBX piston through.

So I was in New Zealand recently and a local seller of some [apparent] renown was selling a sandcast for $80,000 NZD. The frame number and engine number were 6000 numbers [give or take] apart and I suggested that he should make a note on his ad that the engine wasnt the original engine. Well all hell broke loose and he accused me of calling him a  liar, cheat and crimnal and eventually he blocked me from Trade Me [the local sales site]. Subsequently he changed the ad to make comment that the guy he bought the bike off [a renowned US restorer who he wouldnt name] had gotten a Certificate of Authenticity from the 'official' Sandcast Authority' certifying it was genuine.
While I didnt claim nor infer it wasnt genuine, all I had done was suggest [so that he couldnt ever be accused of misrepresentation] that the engine likely wasnt the original. Its currently for sale for $60,000 NZD without NZ registration or much else for documentation.
What Im seeing down there is the covid-driven collector madness of 2 years to 12 months ago has softened and prices for all 'collector' grade bikes has dropped by 10-20%, with the exception of the aforementioned CBX's, which just seem to climb higher by the day.
In one respect I hope he gets his $60,000  as its increases the value of my collection through the roof, but at the same time I could see a few years down the road a disgruntled investor being mad as hell when he cant get his money back because the engine isnt the original one. Yes it may be a 'genuine' sandcast but where does one draw the line as to its true value. I guess the market will tell us the answer to that!

On a separate matter, I have been offered frame #4262/ engine #4268 but cant find out any more about the bike other than its an older restoration, with 300 series pipes, but everything else appears on the surface to be correct. Im going to look at it over the weekend to see just how genuine it really is.  I have my 40+ item list of differences to start. Stay tuned.
Al