Just had a look at the video posted earlier plus other ones on the same subject...
1st the cheating: they fit guides with loads of play to amplify a small wobbly phenomenon and frighten you into buying whatever they wish to sell you...
Use your head, don't just believe what is thrown under your eyes...
They also talk about excessive/unwanted spring and valve rotation
Actually, on a side valve, valve and spring rotation is a feature you want to promote, not hinder...
It allows your valve to wear evenly, clean your seats and distribute around the excessive heat generated by this overhanging mass of cast iron that holds your valve pockets...
See Thompson valve RotoCap borrowed by HD from some industrial engine and fitted in KR from the early 60s... 18212-60R... Basically a cruder version of a thrust ball bearing.
Patrick