DATE CODES

[kp]

Those of you that own/have owned/just know about,t the Z1 Kawasaki will be all to familiar with the extensive use of date coding on numerous parts. The importance of these codes to the Z1 restorer/collector/owner cannot be understated and has a significant impact on values. The types of codes vary from the simple year month code, the Showa date method (http://www.i18nguy.com/l10n/emperor-date.html) and another obscure variation such as a day/month time period was also in use.
Within "our" group there is not a lot of information around date codes on sandcasts, their usage or the importance of having parts correspond to date of production line manufacture. We tend to relate certain parts to blocks of VIN/Frame numbers such as early bikes VIN's have certain part differences to later bike VIN's. Surprisingly, there are numerous date stamped parts on our sandcast bikes some of which are easily understood whilst many parts have less than clear date codes but they are date codes nonetheless. Some of the information provided during Mark's restoration was groundbreaking IMHO so we should add to those findings
I'm thinking that many stamped codes are not very well understood within our group and think maybe it's time we turned our attention to understanding and interpreting these codes. I can think of two examples of stamped codes which are certainly not understood by myself. The codes on Shocks and the disc code are the two I refer to. The Z1 codes on the shocks are a simple month/year code whilst their disc code is a Showa code (7=72, 8=73 etc)
This is my contribution to some discussion. There is one clear example of date coding that causes me a lot of confusion and is the dating used on side covers. My own view is that side cover date codes were not used on original production line fitment BUT I could just as easily be wrong in this view. Nevertheless, a side cover dated 3 70 would not be correct for a 1969 sandcast if it can be shown that date coded side covers were fitted during production.
So can I PLEASE ask for contribution to this topic. We sort of know about fuel tank dating as well as engine case dates but there is a lot more we hopefully can get info on so all contribution will add to our knowledge base. I would hope we can obtain some definitive answers/information.
Again I would ask for contributions to this discussion

[Steve Swan]

Good stuff, KP !   I edited my reply a bit. 

Perhaps a reasonable starting point would be to list every part known to have a date code.  And a list of parts who's codes don't appear obvious as date codes so perhaps we can figure out their relevance as time passes by.  

i can look to see what is visible on 232.  Unfortunately, it's been together since 2005, so being able to visualize some of the codes won't be possible.  i remember seeing various stampings on various parts when i had 232 apart, regretfully I did not write them down, back then we did not know as much as we do now.  Wow, that was almost 12 years ago....

[Steve Swan]

Stamped figures on 232 disc = Q 42 B

232's shocks were replaced whilst retaining original "7 spring" springs.

[Steve Swan]

i have a spare set of very clean original "7 spring" DeCarbon shocks stamped markings "4 H" followed by a Japanese character.  these markings are on the outer aspect of the inside clevis of shock. 

2157 has the very same stampings as per above.  i deem 2157 chassis as a reliable example of a relatively unmolested Fvin.

[kp]

I'm thinking, like kawasaki the shocks are mixed dates. 4=69 and H=August. Has anyone got some codes of their original fitted shocks?

[Sgt.Pinback]

I'm thinking, like kawasaki the shocks are mixed dates. 4=69 and H=August. Has anyone got some codes of their original fitted shocks?

Kerry, I doubt that  "4" = 1969 on Kawasaki parts.

E.g. on a Kawasaki Z1 clutch lever holder you may find "4H" giving August 1974, or on  a Tagasago Z1 rear rim "3E" saying May 1973.
(of course, there was no Z1 in 1969)

[4pots1969]

That's the mark for the date of the shock absorbers? (Mark #97)

[4pots1969]

i have a spare set of very clean original "7 spring" DeCarbon shocks stamped markings "4 H" followed by a Japanese character.  these markings are on the outer aspect of the inside clevis of shock.  

2157 has the very same stampings as per above.  i deem 2157 chassis as a reliable example of a relatively unmolested Fvin.

Steve, It is possible to have a photo of shoks stamped markings?

[Sgt.Pinback]

That japanese character on K0 shocks looks like a Katana sword symbol.

[kp]

I'm thinking, like kawasaki the shocks are mixed dates. 4=69 and H=August. Has anyone got some codes of their original fitted shocks?

I doubt that  "4" = 1969 on Kawasaki parts.

E.g. on a Kawasaki Z1 clutch lever holder you may find "4H" giving August 1974, on  Tagasago Z1 rear rim "3E" saying May 1973.
(of course, there was no Z1 in 1969)

I'm not referring to 4H being a Kawasaki part, rather I'm referring to Steve's shocks where he stated his CB750 shocks are marked 4 H. I suspect a 4 would be 69, the H could easily be July rather than August. As for Kawasaki Z1's. I do know about Z1 markings I own 2 x 1972 models (VIN 94 and VIN 743) and a 1973 model (VIN 9493) You are correct that 4 for Kawasaki can = 74 but can also equal 1969 for Kawasaki as H1's also are coded. In most cases with Honda I have found 4 is a Showa code and = 1969. Kawasaki Disc is Showa where 7 = 1972 and 8 =1973, The Kawasaki discs also have an Alpha code so the Honda shock referred to by Steve maybe also have a Showa year code and an alpha code. This is why the thread was commenced so we can more analyse what members can report.

Edit:I refer to 4 = 1969 or 7 = 1972 In many cases where a Showa code is used the first digit id dropped so 44 becomes 4 and 47 becomes 7 Sorry for any confusion Later codes are often seen as a double numeral after 49 i.e. 50 rather than 0
There is one issue with the Alpha codes used by Kawasaki. These alpha codes do not always follow the pattern of alpha A,B,C,D,E etc corresponding to the month cycle of 1, 2, 3, 4, 5, etc Generally they do but not in all circumstances.

[kp]

In relation to the shock photo posted, generally the shock codes on 69 bikes is metal stamped and appears on the inner side of the bottom mount ie.: closest to the wheel. The shock letters/numbers in the photo look to be dot etch printed rather than stamped and is shown on the outer face of the bottom mount

[Sgt.Pinback]

Kerry,

on my SC (# 1983 build date May 1969) the showa shocks are coded 4H (plus that "katana" symbol) as well.
I am pretty sure that those are the genuine shocks the bike came with so August would be too late.

I will have a look on the shocks of my diecast, still with the genuine showas, if they have 4H as well.

If this is this case, I would say 4H stands "four Honda"    



OT:

Kerry, do you have an idea who made the Z1 shocks?

[Steve Swan]

i have a spare set of very clean original "7 spring" DeCarbon shocks stamped markings "4 H" followed by a Japanese character.  these markings are on the outer aspect of the inside clevis of shock.  

2157 has the very same stampings as per above.  i deem 2157 chassis as a reliable example of a relatively unmolested Fvin.

Steve, It is possible to have a photo of shoks stamped markings?

Gerard, i'll get pic in next few days.

[Steve Swan]

Kerry,

on my SC (# 1983 build date May 1969) the showa shocks are coded 4H (plus that "katana" symbol) as well.
I am pretty sure that those are the genuine shocks the bike came with so August would be too late.

I will have a look on the shocks of my diecast, still with the genuine showas, if they have 4H as well.

If this is this case, I would say 4H stands "four Honda"    



OT:

Kerry, do you have an idea who made the Z1 shocks?

Uli, if "H" stands for "Honda," then shall we expect ALL shocks fitted to Honda have "H" stamped on them ?  

Do Kawasaki shocks have "K" stamped on them ?    And Bridgestone shocks have "B.S." stamped on them ?

[Steve Swan]

I'm thinking, like kawasaki the shocks are mixed dates. 4=69 and H=August. Has anyone got some codes of their original fitted shocks?

Kerry, I doubt that  "4" = 1969 on Kawasaki parts.

E.g. on a Kawasaki Z1 clutch lever holder you may find "4H" giving August 1974, or on  a Tagasago Z1 rear rim "3E" saying May 1973.
(of course, there was no Z1 in 1969)

Uli, What do you believe the "4" stands for ?