Harley Davidson Sportster 1970-2003. Owner's Manual - page 2
Every 5,000 miles (8,000 km)
21 Transmission and primary chaincase oil - change
1 The transmission and primary chaincase are lubricated by the same oil
supply. Before changing the oil, warm up the transmission by riding the
bike so the oil will drain easily. Be careful when draining the oil, as
the exhaust pipes, the engine, and the oil itself can cause severe
burns.
2 Prop the motorcycle upright over a clean drain pan. Remove the
transmission/ chaincase oil level plug to act as a reminder that there
is no oil in the transmission.
3 Remove the transmission drain plug from the bottom of the primary
chaincase and allow the oil to drain into the pan (see illustration).
Discard the sealing washer on the drain plug; it should be replaced
whenever the plug is removed.
4 Check the condition of the drain plug threads.
5 Slip a new sealing washer over the drain plug, then install and
tighten the plug to the torque listed in this Chapter’s Specifications.
Avoid overtightening, as damage to the transmission will result.
6 Before refilling the oil, check the old oil carefully. If the oil was
drained into a clean pan, small pieces of metal or other material can be
easily detected. If the oil is very metallic colored, then the
transmission is experiencing wear from break-in (new transmission) or
from insufficient lubrication. If there are flakes or chips of metal in
the oil, then something is drastically wrong internally and the
transmission will have to be disassembled
