9 RM's in the garage and another 3 that have been in my possession at some point and all have had the "All Balls" treatment. From my experience, this is the most efficient way of doing the task.
1. Grab a heat gun and apply liberal amount of heat to the tripple clamp. (No oxy!
)
2. Press the steerer tube out of the lower clamp.
3. Machine the steerer tube down a further 5mm
4. Very important that the step left in the steerer tube is radiused or your setting yourself up for disaster!
5. With the tube still in the lathe give the lower bearing surface a super fine linish but keep away from the triple clamp section. Remember this area was never designed to have a taper roller fitted and the surface was never prepped for such. (If it had ball bearings originally)
5. Grab the heat gun again and heat up the lower clamp and press the steerer back in.
6. Heat the lower bearing inner and press the lower bearing on.
From ExperienceSuzuki weld the nut into the top of the steerer tube which makes it difficult to get a true centre. As OLDFART explained you'll need a decent lathe with bed clearance to machine with the lower clamp in place, can be difficult if all you've got is mates with hobby size lathes. I've seen two steerer tubes on zooks snap at the step on the newly machined surface, add a radius and you won't have a drama. Use heat (no oxy!) as I've seen so many bearings "pick up" on shafts that weren't meant to have taper roller from production. A bit of heat swells the bearing enough that this no longer becomes and issue.