ORIGINAL: irocbsa
I'm guessing that the crankshaft on the glow engine is not hard enough to accept a roller bearing. We would need to get data on the Rockwell harness of the material the crank was made from.
The shaft hardness must be Rockwell C59 minimum and a maximum roughness of 15 microinch AA.
http://www.maintenanceresources.com/...ings/rbshf.htm
If you had to change the crank pin....A good machinist and a gage pin the size you needed would do the trick.