Interesting read on the YS power website regarding valve clearance.
It turns out that not only were there differences in the cam timing instructions between the English and Japanese language instructions on certain models, but the valve clearance procedure is also different.
The English instructions tend to say 0-0.1mm clearance at TDC
The Japanesese language instructions roughly say 0-0.1mm at one full crank rotation (180deg on the cam) from full lift of the respective valve.
In a perfect world both methods "should" yield the same result, but with a worn cam and crank who knows?