How Do You Change A Crankcase Breather Valve On A 1989 Harley-Davidson?
Harley-Davidson Evolution motors use a dry-sump type oil return system. Oil is pumped into the tappet blocks, rocker boxes and bottom end bearings. All other components are lubricated by splash and drip. Gravity collects the oil in the bottom of the crankcase where it is picked up by the flywheels and removed by the oil scraper. Oil from the scraper drains into an oil gallery next to the breather valve. The breather valve controls the oil in the gallery. A vacuum forms when the pistons are on the way up and the breather valve is timed to open when this vacuum is being generated. The vacuum sucks oil out of the gallery and into the oil pump pickup area, where it is then pumped back to the oil reservoir. Elevate the rear wheel of the bike with a bike jack. Place the transmission in first gear with the shifter. Remove the push rod cover clips carefully with a pair of pliers. Slide the upper push rod covers down to expose the push rods. Rotate the rear wheel forward and watch the push rods
