The "R254" crank and connecting rod material is 20CrMo as same piston pin meterial. it is not common steel material.
So, "R254" crank shaft and connecting rod have more strong durability.
"R254" crank shaft use the normal dimensions ball bearings(6001 series).
So, all user for "R254" crank can purchase the crank ball bearings(all 6001 series bearings) in their nearest bearing shop in easy.
"R254" crank main shaft dimensions is same(straight dimensions).
So, 4 crank ball bearings use of crank case.
"R254" niddle bearings size(only length) for connecting rod two ends are bigger more than Zenoah connecting rod niddle bearings.
So, the connecting rod and niddle bearing have more strong durability.