This is a 1973-74 Motobecane Grand Record frame. Here's the tells:

Standard Nervex Professional Lug.



Proprietary Motobecane Nervex lugs. This is my 1971-72 Grand Record.

Motobecane used these plastic head tube badges on some bikes from 1971-73. Note the Stronglight Competition V4 headset.



Vagner DP+ chevron top fork crown.



Semi wrap around seat stay tops.



The OP's frame has a poor quality rattle can paint job.

The Pivo stem was used on 1973-74 Grand Records.

The tubing on pre-1977 Grand Record frames was butted Reynolds 531 throughout. After that it was butted Vitus 172 tubing.

The seatpost should be 26.4mm but possibility 26.6mm on a few Reynolds 531 frames. 26.8mm doesn't sound right.

For a lot of reasons seat tubes get out of round and so people use undersized seat posts. (but not oversize)

Measuring the top tube diameter is the quickest way to determine metric or "imperial" inch size tubing. A metric top tube is going to be slightly larger than 26mm while inch size is slightly larger than 25.4mm. (slightly larger because of the paint thickness).

So, I think that it is a 1973-74 Motobecane Grand Record frame with almost no original components.

verktyg