Every experienced mechanic has a cabinet full of go-to chemicals that help make routine maintenance easier and tackle repairs that are not so routine. Here's a short list of the essentials, most of which you can find at your local auto-parts or home-improvement store.
• Cleaners and degreasers. Industrial solvents are nice to have but hard to find in small quantities. Better to have a can or two of electrical contact cleaner, which is really useful for removing grease and grime; the caveat here is that contact cleaner can damage plastic and some paints. For heavier grime, a heavy-duty degreaser like Simple Green or any of the "citrus" mixes will work. Chains respond well to simple, cheap kerosene, though there are dedicated "chain cleaners" in the powersports world.
• Grease and anti-seize. Waterproof grease will accommodate most of your needs for lubing axles, wheel bearings, and other things like control pivots and sidestand bolts. A dedicated high-temp anti-seize is useful for exhaust couplings and for spark plugs. (Warning: Use a very small amount on spark plug threads, and keep the lube well away from the tip.)
• General lubricants and penetrants. Have a can of oil-based lube handy for cables and other light-duty needs. We always have a can of true penetrating oil around for those nasty stuck parts. Oh, and don't forget a dedicated chain lube or chain wax. WD-40? Sure, it's good for freeing seized hardware—though not quite as effective as a dedicated penetrating oil—and is very effective for removing sticker residue.
• Glues and adhesives. High-temperature RTV (room temperature vulcanizing) silicone is always useful, and we always seem to have some five-minute epoxy around. Quick-setting "super glue" can make quick work of bodywork fractures.
• Thread lockers. While there are many grades of thread lockers, you'll really only need two, generally referred to by the Loctite-brand orthodoxy: red or blue. Red thread locker (Loctite 271) is meant for permanent locking and sealing. Blue (Loctite 242) is designed to keep hardware from vibrating loose but permits intentional removal.
Depending on how much of your own work you do, add brake fluid, coolant, a quart of engine oil, and dielectric greases to your chemical arsenal. And because most of the really useful chemicals aren’t kind to your skin, get disposable nitrile or latex gloves to wear while you use them.