Nobody looking at a finished model can name what is different, but everyone sees it. Turned fastener heads from about half a millimetre replace the soft bumps that moulding leaves behind, and because metal catches light differently from paint the detail works without any highlighting. The selection covers several diameters and head shapes, enough to dress brake discs, bodywork and an engine block, and one packet normally lasts several builds.
Below you will find how to judge the right size and how to seat the heads so they look like fasteners rather than nails.
A real motorcycle is held together by dozens of visible bolts, and those are exactly what the kit leaves out. Miniature turned hexagon heads, nuts and rivets in diameters from 0.5 to 1.5 millimetres restore the three-dimensional, metallic look of a joint. Resin hose fittings form a separate group, running from 1.2 to 2.5 millimetres, and are chosen against the hose rather than against a fastener size. They are not functional screws: the heads drop into pre-drilled holes and are glued in place. Alongside plain hexagons there are lightened racing heads of the kind circuit machines carry.
Work from the actual size of the fastener. A wheel-spindle bolt on a 1:12 motorcycle kit will take a head of about a millimetre, while bodywork fixings are finer. A photograph of the real bike settles most questions. When in doubt choose the smaller diameter: an undersized head passes unnoticed, an oversized one looks like a nail driven through the fairing.
Hexagons with a washer read as engineering and suit the running gear and engine. Countersunk and lightened heads belong on bodywork. Mixing several shapes across one model looks far more honest than using a single type everywhere.
Fasteners look wrong when they are evenly spaced rather than placed where the real machine has them, so work from a photograph and mark the positions out. Pencil them in before you drill, so every hole is deliberate. Drill slightly undersize, test the head dry, and only then commit adhesive. Cleaning up a hole drilled in the wrong place on finished paint is a miserable job.
Other kinds of upgrade are sorted by type in motorcycle model accessories.
