Joined Jan 2015
277 Posts | 157+
Winnipeg, Canada
Yes, you are safe to do this. The only way you could mess it up would be if you unscrewed the nut or bolt all the way and it fell off (and even then you could retrieve with a magnet easily enough).
The 1/6th turn method (don't know who decided to suggest 1/8th turn) is the way to go for me on my 650. I haven't checked if the valve shaft tops and domed (or if the tappet are cupped), but there is no way for me to get a feeler gauge in there. Maybe if you buy one of those special KTM ones (or make your own), then the feeler gauge would work. But if your tappets are cupped or valves domed, the feeler gauge method isn't accurate.
You may already know this, but clearance is 0.12mm ~= 0.005"
Screw pitch on tappet = 0.75 (mm)
1/6 x 0.75mm ~= 0.12 mm
1/8 x 0.75mm ~= 0.09 mm (too tight and therefore wrong as per manual)
