Harley-Davidson’s reputation has been built around the performance and reliability of their motorcycles. But, each bike made by the company relies on a few basic maintenance routines, such as changing the oil in the engine, primary, and transmission compartments, to protect it against damage from premature wear. Details and information, specific to your motorcycle, such as drain plugs locations, oil quantity, and torque specifications can be found in a service manual. If you have access to a service manual for your motorcycle, use it.
Although the process is fairly straightforward, there are a few items to take into consideration before beginning. First, gather the materials you will need to perform the oil change, such as a oil-catch basin or container, rags, and any tools that you may need. Be sure that you have the appropriate oil filter for your bike’s motor. The Twin Cam series motors used in 2001 and newer Harley-Davidson motorcycles require an oil filter that is capable of filtering particles smaller than 10 microns, due to the smaller oil channels used by the motor. Using a standard filter will allow larger particles to pass through the filter and will clog the oil lines. Also, be sure to have replacement gaskets, drain plugs and O-rings on hand. Ideally, you should replace these items at every oil change, but you may be able to reuse your existing gaskets and plugs if they are undamaged. Finally, it is best if you allow your motorcycle to warm up for a few minutes to help the oil flow during the draining process. Once warm, let the bike rest for a few minutes so that you don’t burn yourself.
Before you begin, locate your motorcycle’s oil drain plug. The location of the engine oil drain plug can vary between the different Harley-Davidson models, but most have the plug placed directly under the motor. Sportster models, however, will use a drain hose. Refer to a service manual for drain plug locations of your specific model. Once located, place your oil catch basin directly below the plug. Inspect the drain plug’s O-ring and replace it if there is any signs of wear to prevent leakage. Once the oil has been drained, remove the old oil filter and discard. Your new oil filter will need to be filled with about 3 to 4 oz. of oil before being installed. To help seal the filter, coat the inner lip with oil and hand tighten the filter into place. Fill the engine with oil, using no more than 3 quarts to prevent over filling.
The primary fluid is drained by removing the drain plug directly below the round “derby” cover on the left side of the motorcycle. You will need a Torx 40 socket and socket wrench to remove the plug. Again, inspect the plug and O-ring and replace if necessary. While the fluid is draining, remove the derby cover and primary inspection cover, a rectangular cover to the left of the derby cover. Replace the derby cover and inspection cover gaskets, if needed. Once the fluid has drained, replace the drain plug and re-fill the fluid through the inspection port. You will need no more than 1 quart to re-fill, with the fluid level just touching the bottom edge of the clutch basket (viewable through the derby cover hole). Replace the covers and tighten all bolts before moving on to the transmission.
The transmission fluid is the simplest part of the process. Loosen the transmission oil dip stick drain and remove the drain plug, usually located directly under then transmission. Once drained, refill the transmission fluid through the dip stick’s filler neck, using no more than 1 quart to prevent over-filling the transmission.