Here's the procedure we used, as "professionals"
in our bike shop (in the 1970s). I wrote it down so my mechanics wouldn't forget a step, and it worked perfectly for up to 3 years (that was the longest we ever stored one):
1. Change the oil, then run the engine. Then clean it real thoroughly with a hi-pressure cleaner ("quarter car wash" is good), grease the swingarm, oil the chain and, if your bike has cables without the plastic inner liners, oil the cables. If your clutch lifter is a greasable type, grease it.
2. Remove the sparkplugs, squirt in about 1/2 ounce of oil (3 tablespoons) in each cylinder. Slowly turn the engine over 4 times, put the plugs back in (fresh plugs are better), tightened normally.
3. Drain gas from tank, petcock bowl, and each carb's bowl (remove bowl for best results, see below...). Get a long spray tube for CRC or WD40, and spray the inside of the tank, don't miss the top, gas cap gasket, petcock bowl and its fuel gasket, and each carb's innards and float bowl (go lightly in the later items, more in the tank). Alternately, remove the tank, pour some CRC or WD40 inside and roll it around thoroughly, let the stuff drain THROUGH the petcock, and close it all back up.
4. If you have a wet-sump bike, add 1-2 quarts more oil (i.e., fill it up) to cover the gears and bearings. By the way, storage oil quality and weight is unimportant, as you must drain it all anyway after long-term storage, as it absorbs water from the air while it sits. Normally, the heat of running would burn off the water, but it won't, now.
5. We always added proper air pressure to the tires and checked them every month, but had the wheels up off the ground. The air pressure procedure is debate-able, I think...
6. Wax the whole bike (except windshield, if so equipped), not with Carnuba wax (it absorbs water too much). If you are so fortunate as to have access to a fogging gun or paint gun, mask off the plastic parts (instrument glass, windshield, side covers) and spray with WD40/CRC or cosmolene instead of waxing.
7. Remove the battery.
8. Electrics: add a drop of oil onto the big posts of the starter solenoid, each of the 6 contacts for the alternator (unless yours has the little black rubber covers on them), and the voltage regulator's 3 contacts. No need to pull them off, just add the oil to close them in from air and water. (This is actually a good thing to do regularly, anyway.)
9. Extra-thorough: open up the switch modules on the handlebars and spray a little CRC/WD40 on the switch contacts, then close them back up.
You will likely find, if stored over 2 years, that the fuel lines will require replacement because the ethanol in our gas today extracts the flexibility from them, and having no fuel at all in them will later make them brittle and leaky when you start it up again. We used to replace them when going into storage as a method of solving this problem "up front", even before ethanol appeared, if the bike was at least 2 years old.
