A nice modification on the steering stem of most motorcycles, is to replace the stock ball bearings with taper roller bearings. E.g check the lower part of the photo below with the Nsr250 steering head bearings. Bearing assy consist of a cup and a cone ball bearing with the balls held in place by a suitable cage. Even though this method was even used on later racers, they are considered old-fashioned.
On the other hand, taper roller bearings give excellent results and a smooth steering (less head shaking) as they kind of act as a soft steering damper. Only drawback is that installation procedure takes a little bit more time as alignment isn't as easy as using the stock ball bearings.
Nsr250 ball bearings, stock and taper roller on top.
Part numbers are Koyo 32006JR (lower bearing) & NTN 4T-CR-0574(top bearing).