Of all the parts used in a parallel twin, these are on the top of the list of hard to find items. Not a single bearing distributor nor manufacturer has these bearings in their standard supply, so the best (economical) decision is to make them yourself.
The design has been slightly adjusted with more lubrication groves in the flange to accommodate the axial load of the crank, and the groove in the inner diameter is now whole as compared to the original. The first test samples were made of Aluminium bronze, which was used as bearing material in heavy gas powered combustion engines for the crankshaft and camshaft and rocker arms, hens the first reason for selecting them.
The did not pass the test, as the crank locked up twice on the dyno once above 4000rpm. The cause was found to be the wrong material, and this was supported by literature on bearing designs and backed by experience from several engine tuners.
So with more information I set out to find more suitable material and have at this moment put out quotations. While the test specimens are made, a separate engine will be put together with these new bearings and bolted into leftover GTV frame for dyno endurance testing.