The so called K0

[Steve Swan]

Hi Derrel,

What i'm going to write is based on my reading of official Honda USA publications, nothing else.  

As far as my logic is concerned, when it comes to the term "K0," not using Honda literature as the official source amounts to hearsay or wishful thinking.  

As far as  the CB750 was/is concerned, during 1969-70, Honda never used "K0" as a model designation on any CB750.  The term "K0" cannot be found in Honda literature until the very late 70's.  When Honda began using the "K0" as a model designation in their Service and Parts literature, they used the term "K0" to designate ALL CB750's beginning with vin 1 through 44649.  (in the USA, the K1 model began mfgr at vin 44650)  

According to Honda literature, there never was mention of a sandcast model.

In England, for a brief period of time, there was  allegedly  around 30 some odd machines  someone  allegedly designated as "K0".  These machines allegedly had the "one piece" carb linkage instead of 4 individual cables.  Who came up with this terminology is unknown.  If any of these machines ever existed remains controversial.  Allegedly, these "K0" machines were built at the very end of the pressure cast run, i.e. around the end of vin run 44649.  I am aware (2nd hand) of possibly one of these "so called K0" bikes being in existance.  

For the sake of CB750 Model designation, myself, IF i am going to "toot my purist horn" using only Factory information from 1969-70, i cannot accept the term "K0", because the term "K0" never existed, as far any CB750, in 69-70 was concerened.  

I will accept the term "so called K0", because Honda did 'so call' the 1969-70 CB750 the K0 in their literature printed around the late 70's or ealry 80's.

The term K0, Honda used as a model designation for all CB750's built 69-70, up to vin 44649.  

Enthusiast glommed on to the term "K0" to described what bike they thought they had.

For me, for vin 1 - 44649, there is only ONE model designation, as used by Honda, 'in the day' and that model designation is CB750.

We use the term K0 on Sandcast Only.  In fact our club is named Sandcast/K0 Only Owners Club.  It''s easier to say than sandcast/pressure cast owners club.  Using K0 is an easy and simple way to get thte point across what machines our club caters to.

Your bike simply has a pressure diecast (post sandcast engine in it, as far as i would know, nothing else.)  Frame probably received this engine d/t the frame's original sandcast cases being broken.

Also, bear in mind, what I've written is based on my knowledge of factory printed matter intended for USA use only.  Does not take into consideration the non-USA export markets Honda shipped to.

Hope this helps.  I've taken your email and my reply and started a new thread on the BB.  I feel questions like yours shuld be on the BB to hopefully be exposed to a population greater than 2, so we can possibly learn more as to whether or not Honda actually produced a bike with linkage carbs using the body work of the sandcast/pressure cast bikes.

Sincerely,

Steve Swan



--------------------------------------------------------------------------------
From: Derrel Weaver <darkwood@hotmail.co.uk>
To: sandcast232@yahoo.com
Sent: Sat, February 12, 2011 8:18:41 AM
Subject: CB750 Engine number mystery!

Hello Steve
Hope the new year has started well for you and your family. Weather is normal misery over here in England at the moment!
Won my first prize of Best Honda In Show at the Stoneleigh Park event a couple of weeks ago, so I'm well chuffed.
I'm still trying to place my mysterious engine. At 1008971 it is Pre KO according to my information. But Post Sandcast.
My book by Peter Shoemark states the KO engine numbers start from 1044848. And that surely makes it later than mine. It also states... "In most respects the KO bore a very close resemblance to the CB750, but featured rocker arm and linkage type carburettor bank in place of the cable operated system.".. But mine has the original separate cable system on it Steve as you can see!
It's obviously a replacement engine from Honda as we know. But what does it fall under? Were there a limited number of engines Honda produced Pre-KO as replacements for the Sandcast problem with the shattering crank cases? Does that mean this is rare in itself? Or is everything pre-K1 classed as KO?
I was hoping the Club could help me solve this mystery.
Also read the other night in the new book I bought at Stoneleigh Park....The Essential Buyers Guide Honda SOHC FOURS. By Peter Henshaw. That all the engines were made in a separate factory to the frames. And there can be anything up to 2000 numbers between frame and engine numbers.
Its all a mystery still. But I would love to find out where this engine came from and what it really is.
You have it listed as a KO replacement in the VIN Listing, is that what I tell all the people who always ask at the shows? Or is there another name for this SOHC?

Talk Soon.
Many Thanks
Derrel Weaver
Number 150.

[hondasan]

There is a Honda UK produced publication from about 1973/4 called "Which Model" that provides the following data...

CB750 - "The first Honda four cylinder production motorcyle", quoting starting frame / engines numbers of CB750-1000001 / CB750E-1000001.

CB750K0 - "This version of the 750-4 appeared during the transitional period from CB750 to CB750K1. The machine embodies only some of the CB750K1 modifications, and in all 36 units were sold in the UK". Frame numbers are quoted as being within the range 1044826 to 1045147, and engine numbers within the range1044848 -1045147.

CB750K1 - "Successor to the CB750 and CB750K0"

Over the years certainly 5 or 6 true "K0's" have surfaced in the UK. Essentially, they seem to be CB750's fitted with K1 carbs / airbox. I am pretty sure I have seen reference to them also having 18 / 48 tooth final sprocket sizes too. Also have read somewhere a refernce to there being approx. 120 true K0's sold worldwide. Certainly as far as Honda UK was concerned, the K0 was a real model variant.

The use of K0 as a description for any pre K1 die cast engined CB750 is likely just one of convenience which has taken hold such that it is now accepted by most as being accurate.
You can imagine the difficulty trying to describe  which "K" model your CB750 was to a parts store man in the late 70's. Easy with the K1, 2, 3, etc, but how to convey that yours is not a K"anything" (ie, before K1). Easy, just start using "K0" for anything before the K1. And then the world discovered "sandcasts" to put another twist on it.

A final thought... A TRUE "K0" is probably the rarest incarnation of the SOHC CB750, even if perhaps not the most desirable!

Cheers - Chris R.

[Steve Swan]

Thanks Chris, for the chronologically sequenced reply taken from Honda UK literature.

Interesting the English K0 CB750 was built beginning vin 44826/E44848. 

The USA parts books state the K1 started 44650/E44806 and the CB750 ended 44649/E44805.

The English K0 was built 176 macines after USA K1 production began.

Was not the K1 an enduring model in England, maintaining the K1 model designation produced for some years after 1971....... ? 

[markb]

Great, interesting info guys.  I'm going to start calling my "so called K0" an early diecast from now on.   

[steff750]

  ah yes that old chestnut  the "K0" the literature states that this was just a transitional model, before the "k1" what people forget was that the early CB750's and sandcasts included, where prone to airbox failure (CRACKING) causing weak fuel to air mixture and overheating, while the carbs would be notoriously difficult to keep in sync and the tools to balance them was very expensive, you could not buy a impact driver in them days .and Mr Honda being HONDA would always seek to improve the model not only CB750's but all his model range ,how things have changed  i have got a old sales brochure from 1970 somewhere calling it the "CB750 DREAM" and that's what it was for me for a long time until i could save enough money to buy one.
              so for me here in the UK they will always be the "HONDA CB750"  period

[hondasan]

There are certainly inconsistencies even within Honda own literature. The fact that Honda UK decided there was a "K0" does not necessarily mean that Japan had officially produced such a thing. Quite likely they were just unofficial "transitonal" models.

Interesting that the US got K1's before the frame numbers identified by Honda UK for the K0. According to Honda UK produced parts list (number 4), the first official K1 imports to the UK started at serial number 1066912.
The UK was obviously a small market for the CB750, and seemed to get them in small batches dotted thorughout production, rather than receiving continual deliveries. We never officially received sandcasts. The earliest official CB750 imported was #1010369 in January 1970. CB750's were still available new in the UK until into 1971. I understand that K1's were not on sale here until about June 1971 (a year after production of them had started), and only ran for about 6 months until the K2 became available early in '72.

Steve - it was actually the K2 which was the "enduring" model here, selling from 1972 right through to 1975. We missed the K3, 4, and 5, but did get the K6 in '76.

Cheers - Chris R.

[kp]

Same here in Oz. No k3,4 or 5 but we did get the k6 and the F models KP

[tomcourtney]

I am sure the UK and other true K0's had painted airboxes and linkage carbs, the only differences from a CB750 were the Carbs, cables and throttle switch block with red kill swich....  tom

[sprunghub]

Pre K1 CB750 Fours were rare in the uk, my own 1970 FLY 77J was one and to everyone it and all others thus were CB750,s, It was only when the K1 came on the scene that anyone riders/owners/dealers  used the term K0, I think owners and others took the assumption that "if the model with the warning lights on the handlebar clamps is the K1  (the only difference most ever saw) then the earlier one MUST be a K0? I have yet to see ANY Honda advert, leaflet manual etc bearing the "K0" and until I do will always call such models the CB750. Apart from anything thing else do you think Honda would go to all the effort of fitting K1 parts to what was becoming an extinct model  or start a series with a "0"?  another point is did the later original CB750's have different clocks with the lights etc,  it all reminds me of the joke re a coin being found bearing the date 120BC!

[steff750]

  @ sprunghub i am curious about your registration plate FLY 77J ,what part of the country are you, I own a1970 blue HONDA cb750 registration is FLK 100J it was registered in september of that year it is a late frame # 103? , could it be possible that both bikes came from the same area or even the same bike shop, i have owned this bike over thirty years and know all previous owners except the original owner ,who had passed away many years ago, but it was said that he purchased this bike somewhere in england (could have been the midlands?) as they where quite rare in south wales at the time  

[Steve Swan]

Chris R's official UK Honda lit from years 73-74 is quite interesting.  

I am not aware of any USA literature that early; both designating the "K0" as a model, as well as, differentiating distinctions from the earlier "CB750" and the later "K1"  machines.

According to Chris's literature, 321 "K0" frames and 299 "K0" engines were built.  With 36 units sold in the UK, where were the remaining 285 units sent ?  

I'd be surprised if many or any of these remaining "K0" units were sent to the USA.  

With 321 frames designated "K0" and a fewer number of 299 engines alloted for "K0" use, i wonder what the remaining 22 "K0" frames had fitted for engines....... ?

[sprunghub]

Uk regs for  NTO 123J type registrations (ie not the new FL 09 AOL type) were originally issued by councils and the last 2 letters were designated to councils, TO, TV, AL for example were all Nottingham/Nottinghamshire ones, the first letter indicated the year first used, but these varied, and may have been used in other decades, ie FLY was used  Jan 1971 on, but also in 1963 and pre war! LK meant your bike originated like mine  in London and FLK regs issued Aug 1970 onwards. As regards "K0" in uk, have still to find anything official to say such called that, no doubt other honda's ie the CB72 altered over the years in little ways? but no difference in title? Different make of course, but the BSA  500cc "Gold Star" was always known as The Gold Star (or Goldie) however it also had official model numbers over the years stating as the M24 in 1938, by 1948 it was the YB34, ' 49 the ZB, '53 the BB, '54 the CB, '55 the DB and '56 the DBD   (all with 34 after) these were all official model types, in some cases, totally different frames or engines, bit like the CB750, K1 K6 etc? (won't even go down the Suzuki  GS1100/GSX1100EZ/GSX1100EF/EG; B&Q, M&S route etc lol)

[hondasan]

My feeling is that "K0" is a term of convenience used now by many to refer to pre K1 / non-sandcast bikes.
If some people find that a way of identifying with such bikes - fine!
I will still however maintain that it is an incorrect generalisation, a belief substantiated by the official HONDA UK publication which clearly identifies the K0 to a specific range of serial numbers. Maybe Honda UK got it wrong, maybe someone at the time came up with the designation to be able to relate to these transitional models (perhaps even to justify to customers buying such bikes new the reason for the detail changes).
Pete Shoemark's "CB750 Super Profile" (probably the first book produced exclusively about the CB750 back in 1983) shows pictures of a UK "K0", registration NBP 770J, and provides some words about this machine. Where he got the information from?, and its correctness???.
I met the original owner of a late UK CB750 on the Isle of Man back in the '80's, who when I remarked that he had fitted a K1 type airbox and later carbs told me in no uncertain terms that the bike was exactly as it had been on the day he bought in new.

As restorers of older Honda's, it is important to many amongst us to achieve factory correctness during that process - that is perhaps when the  importance of knowing whether a machine is a "transitional" one or not andwhich parts are "correct"  is likely to come to the fore, however such a machine is described ("late CB750", "k0", .....).

Chris R.

[tomcourtney]

My take on these Transitional bikes is They were fitted with Linkage Carbs with candy painted airboxes, these K0's were offered in the UK, JAPAN and Australian Markets and maybe elsewhere, They have a vin which ranges above CB750-1044650 the USA K1 start and between the introduction of the K1's in the various other markets. These bikes were not offered in the USA they got K1's way before the rest of the world. Honda offered K1's at different times in different markets and thus different K1 entry vins see your parts book for the different markets, there is a clue in the parts book . I think the carb cable and switch block for the Australian market, i believe these bikes were offered in Japan, UK and Oz, i have some factory pics from back in the day of cb750's with twin cables There is a Factory pic on a Jap brochure taken from the riders position and you can see the early gauges and twin throttle cables..

http://www.motorland.co.jp/cb750four12800811.jpg

.. my bike like this is a 1045xxx and i just bought another and its vin is CB750-1049xxx regards Tom

[tomcourtney]

 

 The term "K0" cannot be found in Honda literature until the very late 70's.  When Honda began using the "K0" as a model designation in their Service and Parts literature, they used the term "K0" to designate ALL CB750's beginning with vin 1 through 44649.  (in the USA, the K1 model began mfgr at vin 44650)  
 

Steve, Not So.... i have found on a American Honda Parts News dated appropretly  April 1 1976 Bulletin No :750-49
Application of head gaskets Model; CB750K0-76
For CB750E-1000001 To CB750E-2352922 (K0-mid K4)
Tom