Crankcase Breathing System - Buell S1 Lightning Workshop Manual

CRANKCASE BREATHING SYSTEM

GENERAL
See Figure 3-43. On piston downstroke, a mixture of crankcase
air and oil mist is vented up the push rod covers (1) through an
umbrella valve (3) in each middle rocker box section. The oil
mist separates from the crankcase air, collects and passes
through a small drain hole (2) where it eventually returns to the
crankcase. The crankcase air is routed through a passage in
each cylinder head. The crankcase air then travels through
each air cleaner breather bolt (4) into a hose leading into the
air cleaner.
b0143a3x
1
4
1. Push rod cover (2)
2. Oil drain hole
3. Umbrella valve
4. Breather bolt
3-32
Figure 3-43. Crankcase Breathing System – Typical Cylinder
3
2