One of the things that I know we all lay awake at night thinking about is ‘what do those markings on Suzuki components mean ?’. So to put our collective minds at ease, I have been doing some checking into how Suzuki marked dates of manufacture on things they made.
John Brookes in the UK operates a Kawasaki Z2 site and first wrote about this topic and he has been kind enough to let me reference some of his material as a starting point for dating Suzuki components. While this information may only be of interest to ‘rivet counters’ or (to use the UK term) ‘anoraks’, with each restoration or even each needed repair, the original factory markings often disappear. This then leaves us with fewer and fewer benchmark examples of what the machines actually looked like, which parts actually were installed and also, what it is you actually are buying when paying top dollar/pound/euro or yen for a supposedly ‘original’ machine.
To quote John: “Anyone who has looked closely at Japanese motorcycles from the Seventies may have noticed various numbers/letters stamped or marked on some of its components. In some cases, these are date codes and it should be pointed out that these date codes relate to the date of manufacture of the part and not the motorcycle. In general it is normal to see a date of between 0 to 2 months before the manufacture date of the bike.
Before reading further, it is necessary to understand a little bit about Japanese dating practices. Since 1868, when Japan switched rulers from a Shogun to an Emperor, there have been four reigning Emperors: Meiji, Taisho, Hirohito (Showa), and Akihito (Heisei). Japan’s traditional era is based on the emperor’s reign and machines manufactured during the seventies were manufactured during the Showa reign. Hirohito (Showa) came to reign in 1926 and therefore a Gregorian date of 1973 would be the 48th year of Showa.”
For the Suzuki years under discussion, you then have the following Showa equivalents: 43=1968, 44=1969, 45=1970, 46=1971, 47=1972, 48=1973, 49=1974, 50=1975, 51=1976 and 52=1977. To further complicate matters, Japanese parts can be dated by either the Showa code or Gregorian code, and abbreviations are sometimes used as well (‘3′ rather than ’73’ to signify Gregorian 1973 for example, and ‘8’ for Showa ’48’ being Gregorian 1973). On top of all this, and to totally confuse things Suzuki went one step further and also marked parts with the actual part numbers, and then wheel rims had a different marking system completely which I’ll get to in a moment.
Most of the material I have is specific to the GT750, but from what I’ve seen it applies to other Suzuki models also. What follow are a few examples – just click on any photo to see a larger version.
I have gone through my gauges for the T500, GT550 and GT750 and so far have found only one instrument that has a date stamp. Referencing the photo to the right, this gauge is off a brown face, KPH 1977 GT750 and the Showa date clearly shows this as a June 8th, 1976 date of manufacture. The others I have often have what appear to be quality control or inspection stamps, but no dates. If anyone else has additional examples I’d appreciate you contacting me.
Carburettors were punch stamped, and then ink stamped after 1974 (depending on the model) and used the part number as well as an indicator to mark left, centre or right as applicable. This is a GT750 carburettor from a 1977 ‘B’ and is clearly marked with a 316, which is the model number for the M, A and B GT750’s and the suffix of ’23’ which is specific to the ‘B’. The ‘R’ indicates it is the right side carburettor. Fuel cocks used a similar methodology.
Takasago supplied wheel rims to many Japanese bikes and had their own date stamping methodology prior to 1977. So when looking at a wheel rim marked as TAKASAGO 2.15 X18 6K 103 JAPAN. it decodes as: the manufacturer, the rim size (2.15×18). and then the date code of 6K which is 1976 and the month of November, followed by the model (103 fitting the GT500, GT750 and other Suzuki models).
For the full version of what I have found so far, please check my web site at this link. So there you go – now we can all sleep at night !