What is the proper way to change Primary Oil on an 89 1200 Sportster?

Can anyone tell me What is the proper way to change Primary Oil on an 89 1200 Sportster? Also what is the best oil to replace it? Thanks

primary oil change on 89 1200 sporty

First, get a "HD" manual and a parts manual. That will help. Are you sure the primary is a chain? Cus, the belt does not take oil. If it's chain drive, it can done like this. Locate the drain plug, drain ,hold the bike upright so most of the oil is out. (Oil filter)?? if so replace. put plug back in drain hole. Oil level hole,there should be plug threaded in the side of the motor. You pull it out, add oil till it comes out of the hole, while the bike in the upright position. You can add the oil throu the primary chain access hole ,in the primary. For oil, iv'e ran just about everything you can think of. but 30wt. should do the trick. make sure no leaks, hope that helped?