You need to adjust the cable at the handle bar end to get the 7.91" or 201mm measurement correct and then at the gear box end to achieve the correct free play at the handlebar lever.
Clutch adjustment is not ultra critical but whatever method you use you are aiming for 2 - 3 mm free play at the handle bar lever and with the handle bar lever at half travel the clutch operating arm should be parallel with gear box endplate to achieve maximum mechanical advantage. This is how clutch adjustment is described in the 1980 owners manual.
The 81 on manual describes the 7.91" or 201mm method which gives the same result and is probably easier to do even if it sounds odd and against your instincts when you first read it. Just do exactly what it says and you will get the right result.
Lou posted a pdf of the 1981 owners manual here
http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1271881232Both methods are also described in the Haynes manual.
