2002 Buell X1: Engine 3-35
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CRANKCASE BREATHING SYSTEM 3.11
GENERAL
See Figure 3-52. On piston downstroke, a mixture of crank-
case air and oil mist is vented up the push rod covers (1)
through an umbrella valve (3) in each middle rocker box sec-
tion.
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 cylin-
der head. The air then travels through each air cleaner
breather bolt (4). Hoses leading from the air cleaner bolts
deposit the air inside the air cleaner’s snorkel.
Figure 3-52. Crankcase Breathing System,
Typical Cylinder
1. Push Rod Cover (2)
2. Oil Drain Hole
3. Umbrella Valve
4. Breather Bolt
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1
4
2
3