[Ratso]

For a race bike, yes (less friction). Street bike, I wouldn't bother.

 

[richbob]

I read about that
The Thackeray washers
Supposedly sap power ??

 

[Ratso]

Minutely, yes.

 

[reverb]

In the 750s rocker boxes the spindles and arms are a bit different so the thackery washers are to the box not to the arms. You need to change one of the plain washers to 1/2. All that to have a better flow of oil there as designed by BSA engineers...something that the workers at works did not liked at all and keep it going the old way. That is showed in not all the manuals but in the later parts books.