A K-Serial frame is a prototype Japanese made frame built in 1982 before the official release of US made frames in 1983. The serials did not have a date code, just a ‘K’ serial which would read ‘SKYWAY K001522’. The serial number only was reset in September 1981 as the new version of the frame was released - the prefixe, where used and suffixes remained the same The location of the stamping of the serial number on the Series 2 frame was also changed somewhere between 918D and 9143D, there are NO frames we know of before 9143D that are stamped in the. 1983 Skyway T/A Original complete bike. I bought this back in 1983 and put it together with various high end parts back in that era This is a one of a kind bike that many cannot find out there especially with the wheels and cranks. When the idea for this site came about. It was to be a place to reminisce about the early days of our sport. It has evolved into much more. It is a community of people who are drawn together by a common bond, BMX. Some of you may have raced, others rode freestyle or some just had fun on a 20inch bicycle during what are remembered by some as the best days of your youth. The actual number. This followed through for all engines, but the frames differed a little as some were used for more than one model so the one prefix was common to sev­ eral. Thus the 1937 M20 numbers began from engine HM20-101 and frame HMI9-101 with the same frame also being used by four other models. The year letters were.

Originally appeared in the UK Vintage Japanese Motorcycle Club Newslettervol. 19, no. 4 (Aug 1996).

There are three different identifaction marks on all Bridgestonemotorcycles. There are the usual engine and frame numbers, with anadditional Vehicle Serial Number on a separate plate riveted to the frame.

The Vehicle Serial Number follows the same format for all models,and uniquely identifies an individual machine as it leaves the factory. Atypical serial number (actually from my own 350 GTR) is shown below:

The Model Code (first two digits) identifies the basic modelfrom which the machine is derived, and the code numbers used were asfollows:

The Month Code (third alpha character) identifies the monthof manufacture and repeats in a 2-year cycle, starting on an even year(1964, 1966, 1968, etc.). Thus, the codes refer to the months inthe table below:

The Identification Number (last five digits) identifies the individualmotorcycle and simply increments for each successive machine built, startingfrom 00001.

The precise month of manufacture is obtained by combining the month code andthe Identification number. No official information is available on productionrecords for each model, but the factory Parts Lists do give specific dates andserial numbers when modifications were introduced on the production line. Itis quite easy to work back from these 'milestone' dates to date any individualmachine reasonably accurately. Relevant 'milestone' dates and serial numbersavailable for the models sold in the U.K. are as follows:

Skyway Frame For Sale

Frame and Engine Numbers

The frame and engine numbers follow different systems for each Bridgestone model.

For the single cylinder models, the enigne number is stamped on the transmission case, and is of the same format as the Vehicle Serial Number previously described. The frame number is stamped either on the headstock (50cc and 60cc models) or on the right hand side of the frame behind the swinging arm pivot (90cc and 100cc models). This number is of the form 'KE 064287'. The prefix letters seem to refer to the Basic Model for which the frame was built, but I have insufficient information to confirm this. The final 6 digits of the frame number form an individual frame Identification Number, again simply incremented for each frame produced.

For the 175/200cc models, the frame number is stamped on the side of the headstock, and the engine number on the transmission case. Both of them are of the form 'TA1-30991'. Here, the last five numbers form the incremental identification number, and the prefix is the factory production code. The 'TA1' prefix was used for 175cc machines, and 'TA2' was uded for 200cc machines. Note, however, that the very early BS200's were built using up the last of the stock of 175cc frames (175 and 200 frames are identical), and these therefore would have had frame number prefixes of 'TA1'.

Skyway Frame Serial Numbers Identification

For the 350cc models, the frame number is once again stamped on the side of the headstock, but the engine number this time is on the upper crankcase, just forward of the rear engine mounting lug. This number is usually stamped quite lightly, and can be difficult to see under the usual layer of oil and road dirt. The format is similar to the 175/200cc but using the 350's own prefix code of 'NA-1'.

It may be of interest to note that the factory production codes can be cast into many components, from speedo drive gears to engine casings. 'NA1' will indicate a 350 part, 'TA1' as 175 part, 'EA1' or 'EA3' a 90 part, 'GB1' a 50 Sport part, and so on.

A final note: As the machines left the factory, the Identification Numbers with the Vehicle Serial, Frame and Engine numbers were unlikely to be the same on an indivudal bike, but were always within 200 or 300 of each other. Any machine with numbers further apart than this has probably had an engine or frame change during its lifetime (apart from the early 200cc machines mentioned previously built with the late 175 frame numbers).

Submitted by Graham Weeks through the Bridgestone Registry. You can write to Graham at 104 Wrington Close, Little Stoke, Bristol, BS12 6ET, England.

Bridgestone Motorcycles pages by Mike J. Brown