I saw something come up on another forum where the poster asked about some numbers stamped into his R90S engine block. These numbers are on the rider's left side on the front facing part of the block, wedged between the points cover and where the sump bolts on. I researched Snowbum's webpage on this and didn't really find any specifics about this time period. He does mention a flat milled surface that is below the left cylinder and above the line for the sump...can't find that on my /7. This flat milled area seems to have shown up in the early 1980s??
The other poster had the numbers "354459" with a "30" and a "38" (30 above the 38) and these two numbers were enclosed in a box. On my September 1977 build R100/7, I only have the number "387508". Taking a cue from what Snowbum wrote, I believe the "38" for my bike represents the 38th week of 1977 and it turns out that falls within September. Most likely the "7508" is the sequence number. Only a little more than 5000 /7s were built for the 1978 model year, but there were more 1000cc blocks made for R100S, R100RS, and R100RT bikes...all being essentially the same but with other engine parts/carb parts being different.
Anybody else have something like this on their pre 1981 bike? Here is my picture...quite dirty.
The other poster had the numbers "354459" with a "30" and a "38" (30 above the 38) and these two numbers were enclosed in a box. On my September 1977 build R100/7, I only have the number "387508". Taking a cue from what Snowbum wrote, I believe the "38" for my bike represents the 38th week of 1977 and it turns out that falls within September. Most likely the "7508" is the sequence number. Only a little more than 5000 /7s were built for the 1978 model year, but there were more 1000cc blocks made for R100S, R100RS, and R100RT bikes...all being essentially the same but with other engine parts/carb parts being different.
Anybody else have something like this on their pre 1981 bike? Here is my picture...quite dirty.
