Motorcycles are hellbent on breaking themselves apart. The vibrations caused by the pulse of their cylinders and miles of punishing asphalt both work to undo all the carefully torqued fasteners that hold the show together. Loctite, manufacturer of thread-locking compounds, has been making certain the world's nuts and bolts stay put since 1956. Clearly the stuff works, but experience tells us that choosing the wrong formula for the application at hand can cause as much grief as losing a fastener altogether.
Purple Loctite Threadlocker 222 is made specifically for small fasteners, formulated for hardware up to 1/4 inch in diameter like set or adjustment screws, or anything that goes into low-strength metals like brass or aluminum. Best used on small threads, it's removable without resorting to heat.
Likewise, Blue Loctite Threadlocker 243 is a medium-strength formula designed for fasteners up to 3/4 inch in diameter that are meant to be disassembled with hand tools. Perfect for body-panel bolts, tank hardware, bash plates, or anything else that you may want or need to remove once a season, the blue goo tolerates contaminants and cleaning products without degrading.
Red Loctite Threadlocker 263 is for hardware you hope you'll never have to take apart again; subframe bolts, engine mounts, and kickstands all itch for the stuff. It's good for bolts up to one inch in diameter and usually requires some heat for disassembly.
Finally, Green Loctite Threadlocker 290 is a wicking compound, which means it's made for pre-assembled pieces. Drop it on, and it will work its way into a fastener's nooks and crannies, sealing everything in place. It's also great for electrical connectors you don't want coming apart.