ORIGINAL: w8ye
The standard 52100 steel bearing with a polymite, or a phenolic ball retainer is best for the high speed situation ...
Jim,
That's what Paul (RC Bearings) offers in nearly all his standard two-stroke sets.
And, BTW, there generally is no difference, in the RPM limit; between bearings with steel cages, and the same bearing sizes with plastic cages.
...And this limit is around twice what most engines are capable of turning...
The advantage of the plastic cage over the steel cage is that if it happens to fragment; the pieces are much less likely to take out the piston/sleeve.
Jeffie,
The problem with Boca, which you so avidly endorse, is that the price they charge for this type of bearing set (which they call 'High Performance'), is as high as what Paul asks for his ceramic hybrid sets.