Combustion gases collect in your oil and form acid. You don’t want that acid sitting in your crankcase all winter eating away at bearings and other expensive parts. So even if you’ve recently changed it, you need to change it again for winter storage. Yes, it’s that important.
Bikes have low clearance and car drain pans won’t fit. So get a low-profile plastic food storage container (no, not from the kitchen) and use that as a drain pan. Spin on a new filter and refill the crankcase with fresh oil.
Some shops think this step is overkill, but it can’t hurt. Fogging prevents corrosion by covering internal engine parts with a light coat of oil. There’s no downside to it. Just make sure you do this step outdoors—it creates a lot of smoke. If your bike needs new spark plugs, install them before you fog the engine. Start fogging by removing the air filter (the fogging oil will clog the filter material). Then start the bike. Spray the fogging oil directly into the air intake as you increase the idle speed to 2,000 rpm. Stop spraying when the engine quits.
Even though you’ve added stabilizer to the gas, you still have to drain the carburetor. Turn off the main gas valve from the tank. Then look for the petcock or drain screw on the bottom of the bowl. Place a folded rag under the bowl and open the petcock. You won’t see a flood of gas—a carburetor bowl only holds about 2 ozs. Close the valve when the gas stops flowing. Spread the rag out to dry (not in direct sunlight) before tossing it into the trash.
On shaft-driven bikes, remove the drain plug and let the gear lube drain out. Then replace the plug, level the bike and refill with fresh lube. Use a bendable funnel and pour slowly until you see oil seeping out of the opening. Then cap the funnel end with a rag (to catch the rest of the oil in the funnel) and replace the filler plug.
Mufflers and air cleaners are “homes of choice” for critters. Keep them out by stuffing a sandwich bag with steel wool and then pushing the bag into the air intake and tailpipes. The bag keeps steel wool strands out of the engine. Use bright-colored caution tape as a reminder to remove it in the spring.
You should already be doing this several times during the biking season. But it’s especially important to spray chain lube onto the chain and into all pivot points (brake and clutch levers, kickstand, fold-up foot pegs, etc.) before storing your bike for the winter. That’ll keep rust from forming on the parts during the winter.
This may sound strange, but a light coating of WD-40 over the entire bike does a great job of preventing corrosion. I got this tip from a bike shop service manager who swears that his bikes come out of storage looking better than customers’ bikes that aren’t sprayed. In the spring, just drive it to a self-service car wash and hose it down. It’ll look great.