Classic motorcycle owners often winterize their classics. Protecting the various components and systems during long periods of storage, such as winter time, ensures the bike will be in good condition when it is time to ride it again. However, if the bike was winterized, it will need some basic maintenance before it is ready to ride.
Assuming the bike was not stored with the tires touching the ground, the tires will only need a visual inspection and the pressures re-setting. However, if the bike was resting on its center stand, for instance, the tires will be slightly indented where they were in contact with the ground. This problem will be particularly pronounced if the tire/s deflated during storage.
To remove the indentation (commonly referred t as a flat spot) the tire should be slightly over-inflated (approximately 20%, for example if the regular pressure is 32 lb's. it should be increased to 38.5 lb's.) for a period of at least 24 hours before riding the bike. Just prior to riding, the tire pressures must be re-adjusted to their normal operating pressures.
If the owner was considering fitting new tires, it would be a good time to do this before riding.
The engine and gearbox oils, along with any associated filters, should be replaced for the new riding season.
If the cylinders were treated with WD40 to stop rusting during storage, the cylinders and valves (4-strokes) should be in good shape and not need any further maintenance.
If engine oil was poured into the cylinders, the engine should be rotated with the spark plugs removed and with a shop rag placed over the plug holes to catch any surplus oil that may be ejected.
This procedure should be undertaken by rotating the crankshaft by hand (a wrench on the end of the crankshaft as against using the kick or electric starters) with the ignition off. Alternatively, the bike can be put into gear (2nd) and the engine rotated via the rear wheel; again without the plugs fitted and the ignition off.
If the bike was prepared for storage properly, a fuel stabilizer will have been added. When the bike is brought out of storage, it will only need new fuel adding. However, if the bike was stored with fuel in (particularly in America), the carbs may need to be fully rebuilt and cleaned to get residue out of the various components.
The first sign that the carbs are gummed up with old fuel is when the bike will only run on choke at small throttle openings - even when the engine is hot. This symptom indicates that the primary jets are blocked. Diagnosing carburetor problems is relatively straightforward but problems can be time consuming and/or expensive to repair.
If the bike was fitted with a smart charger during storage, the electrical system should be good to go. However, if the bike was stored without disconnecting the battery or without using a smart charger, the battery will need fully charging or replacing. A DC voltage check will indicate if the battery is beyond service.
All lights and switches should be checked for correct operation (occasionally corrosion will occur around bulb contacts).
The brake rotors should be cleaned with brake cleaner (not forgetting the section of rotors hidden under pads), and the brake fluid bled. The brakes may not be as effective as they were before storage, therefore the owner must exercise caution when first riding the bike after a period of long storage.