Time for Winter Storage

by Paul Glaves


From the November 1998 BMW Owners News

In many respects, storing your motorcycle can damage it more than riding it mile after mile. But damage from storage can be avoided if the motorcycle is properly prepared. There is no precise definition of  how long a period constitutes storage, but if  you allow your motorcycle to sit unridden for more than 30 days some of the perils of storage will come into play. Certainly, if left unridden for two months or more, some or all storage precautions are a good idea.  Planning for the seasonal storage of a motorcycle over the winter (or hot summer) months requires one level of precautions. Planning for long term storage for many months or years requires an even greater level of concern and effort.

Most potential damage from storage comes from contaminants, moisture, and cold temperatures. The fundamentals of storage preparation involve ensuring that the motorcycle is clean and free of  contaminants inside and out. Much of what you need to do applies to all BMW models. Certain precautions apply specifically to certain  models and not to others. We’ll discuss these differences as we go along.



Most of the moving parts on your motorcycle require lubrication. All of the lubricating fluids in the motorcycle should be drained and renewed prior to storage. Engine oil becomes contaminated as the engine runs. Oxides of sulfur combine with water to form sulfuric acid, and other acidic compounds are also formed. Shafts, bearings, and other surfaces can become etched and damaged if contaminated oil is left undisturbed in the engine for extended periods of time. The transmission, driveshaft housing, and final drive are vented to the atmosphere. Forks are imperfectly sealed. These components accumulate moisture. The moisture condenses as water droplets which are heavier than the oil and accumulate at the lowest points in the component in which they are located. There are two risks from this accumulation of moisture: corrosion and damage from freezing if temperatures drop below 32 degrees Fahrenheit.

Your motorcycle should be ridden at least 20 miles to bring the parts to full operating temperature prior to draining the fluids. Riding for shorter distances may bring the engine to operating temperature but this is not true of the transmission, final drive, and other components. Engine oil should be drained and renewed. The oil filter should be changed. All other fluid lubricants including transmission oil, final drive oil, fork oil, and driveshaft oil where used should be drained and renewed.

There are a number of additional points which should be freshly lubricated prior to storage. These include the centerstand and sidestand pivots, brake pedal pivot, clutch cable end barrels, and brake and clutch hand lever pivots. Winter storage of a few months probably doesn’t require it, but planned long term storage of a year or more would warrant cleaning and fresh lubrication of the steering head bearings, and the unsealed wheel bearings used on air cooled boxers prior to the 1985 models. For long term storage I would also clean and freshly grease the gears used in the twistgrip throttle assembly.



Tubeless tires and inner tubes in tubetype tires do not contain air perfectly, and air slowly seeps out as time passes. You should take precautions so that the tires don’t become low or go flat in storage.

Tires with nylon ply cords will take a set or “flat spot” if left bearing weight in the same position for extended periods of time. Steel, kevlar, and polyester cord materials are much less prone to flat-spotting.

A number of years ago when the majority of motorcycle tires were constructed using nylon ply cords, storing the motorcycle with the weight off the tires was recommended. This remains a good practice for long term storage. I recommend that tires be inflated to the maximum pressure, shown with the load rating, on the tire’s sidewall. The bike should be placed on the centerstand to minimize the weight on the tires during seasonal storage.



Gasoline is composed of a mixture of hydrocarbons and other compounds. Some of the components are more volatile and evaporate more readily than other components. As the lighter, more volatile components evaporate, they leave the heavier less volatile components in the mixture. Gums and varnish form, which can clog carburetor jets and fuel injection pumps and injectors. Problems can be troublesome and annoying with carburetors. Problems will be severe and costly with fuel injection systems. I have worked on several K series motorcycles left in storage for periods of a few months to a few years which have had seized fuel pumps, clogged injectors, or both.

Many (but not all) of the BMW fuel tanks are vented to the atmosphere and may take on airborne moisture. I have seen many steel fuel tanks, particularly on older models, develop leaks at the low spots from rust forming inside the tank. I have also seen corrosion develop inside aluminum fuel tanks.

Storage preparations for the fuel system include efforts to prevent the formation of gums and varnish and the elimination of moisture from the system. I would recommend that late in the season, during preparation for storage, the fuel system should be cleaned using a quality carburetor or fuel injection system cleaner. Cleaners containing Chevron brand Techron are very effective as is Gumout brand. Be careful not to use too much cleaner for the fuel in your tank. Generally, about 1 ounce of cleaner per gallon of fuel is sufficient, but follow the instructions on the label on the cleaner container. Simply add the cleaner to your fuel tank and ride the motorcycle until the fuel has been consumed.

You will need to eliminate any water which has accumulated in the fuel tank. I don’t like alcohol in fuels, but I like water sitting in the fuel tank even less. On carbureted bikes with petcocks, drain all of the gasoline from the tank, add a small amount of Heet or other alcohol based gas drier, and then empty the tank completely. On fuel injected models, ride the bike until the tank is as close to empty as you dare. Add a few ounces of Heet and some gasoline. Ride the bike until that fuel has been consumed.

Store the bike with the fuel tank full. This minimizes the air space in which atmospheric moisture may condense. For storage of 30 days or more, it is a good practice to add a fuel stabilizer, such as Stabil brand, to minimize the formation of gums and varnish in the fuel during storage.



You should change the brake fluid at least once a year. My recommendation is that this service be done in the fall so that fluid contaminated with moisture does not sit in the calipers and master cylinder during storage. Contaminated brake fluid will cause corrosion, and brake calipers and master cylinders are expensive parts to replace. If the fluid has been in your motorcycle for more than 90 days, I would recommend that it be replaced as part of your storage preparations.

K series motorcycles and F650’s should have the anti-freeze drained and renewed. Do not exceed a mixture strength of 50% antifreeze. Follow the mixing instructions on the container. There is some evidence that anti-freeze solutions containing silicates may be harmful to water pump seals. The problems have been most pronounced on other brands of motorcycles which use a different type of seal than does BMW. Nonetheless, I recommend the use of antifreeze which is labeled as “silicate free.” I also recommend the use of distilled water to mix with the anti-freeze to eliminate the introduction of dissolved minerals into the cooling system.



Your battery will require attention during storage. Compared to the battery in a car, your motorcycle battery is electrically challenged and mechanically fragile. A new, fully charged battery contains a number of lead plates suspended in a solution of sulfuric acid electrolyte. As the battery discharges and recharges chemical changes take place. As the battery discharges, lead sulfate forms on the outside of the plates. When the battery is recharged, the sulfate portion of this compound returns to the sulfuric acid electrolyte and the lead is redeposited on the plates. So far so good. But, physically, lead sulfate occurs with two different sets of characteristics. When it first forms, lead sulfate is soft and charging the battery will readily reverse its formation. But after sitting for a period of time the lead sulfate becomes hardened and charging the battery will not reverse the process of its formation. When in the hardened form, the lead sulfate will flake-off the plates and the particles settle to the floor of the battery case.

Batteries self discharge when sitting idle. The self discharge rate is highest when the battery is warm and least when the battery is cold. Of course, clocks and other devices which draw power from the battery will increase the rate at which the battery discharges.

This process occurs in your car battery or your garden tractor battery too, but the process causes more problems in motorcycle batteries than batteries for most other applications. Motorcycle batteries are designed to be relatively light weight and to require small amounts of space. They have a large number of very thin plates. This makes them both mechanically fragile and subject to problems from sulfation. There is limited space at the bottom of the battery case and the sulfate deposits which flake off the plates will short out the plates quickly.

Two other problems affect your battery in storage. If you permit it to become completely discharged and it sits for any length of time, it is not likely that you will be able to recharge the battery. The hardened lead sulfate simply will not permit recharging. Also, sulfuric acid electrolyte in a charged battery will not freeze, but when the battery is discharged the electrolyte is mostly the remaining water and this will freeze. If a discharged battery freezes, usually the case becomes cracked and the weak acid leaks all over your motorcycle.

So, keeping the battery charged during seasonal storage is important. You should recharge the battery using only a low output charger designed for motorcycle use. The charging rate should be approximately 10% (in amps) of the amp/hour rating of your battery. That means a 1-1/2 or 2 amp charger should be the maximum.

For many years I used a system by which each motorcycle had its battery charged for 24 hours, once each month, during seasonal storage. During winter storage this will usually keep a battery charged sufficiently to prevent damage. If you do this there is little reason to need to remove the battery from the motorcycle. I simplify the process by having my charger equipped with a plug which matches the electric vest power outlet on my bikes. Attaching the charger simply requires plugging it into the outlet. Always plug it in to the bike first, then into the wall outlet which supplies power to the charger.

The new style “smart” chargers which detect the battery’s voltage and cycle themselves on and off are a good investment. I have use can vouch for the usefulness of the Battery Tender brand charger.



The exterior surfaces and nooks and crannies on your motorcycle will suffer deterioration if you permit the motorcycle to sit for extended periods in a dirty, cruddy condition. You should thoroughly wash the motorcycle to remove dirt, salt, and other contaminants. I do this prior to doing the storage service.

Do not store your motorcycle outside, exposed to the weather, unless you have no other alternative. Be careful with the use of bike covers. With changing temperature and humidity conditions, moisture will condense on the motorcycle and inside the cover. This will accelerate rust and corrosion. The best place to store a motorcycle is in a cool building - even an old shed if that is all that’s available. I prefer to cover my bikes with an old bed sheet to minimize dust and any stray bird bombs.

A little time spent preparing your motorcycle for its off-season will pay off with many problems being avoided later in its life. <