What different standards exist for crank bolts into modern bottom brackets?
SunRace spec sheets show the crank bolts should be M8x1.0. The bolt diameter is 8mm and there is 1mm betwween thread peaks. This size is by far the most common. However there are other standards. Truvativ seems to have the most variations using M8, M12, M15 plus some self extracting bolts. If the bolts starts but binds it is likely the right diameter but the wrong thread pitch (most likely M8x1.25).