Sym MB10A7-A series Service Manual page 215

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Positive Crankcase Ventilation System (P.C.V.)
1. Construction
Air filter
Flesh air
Mixture gas
Blow-by
Engine oil
2. Principle of operation:
Install a separated chamber on cylinder head, and suck the blow-by gas to the fuel vapor separator
by engine vacuum.
Drill a hole in the air cleaner and install a vapor separator, so that blow-by from crankcase will flow
through a cylinder check valve and then separated by the separator.
The separated vapor will be sucked into combustion chamber by engine negative pressure to be
burned again instead of discharging into atmosphere. Drain liquidized fuel in the drain pipe
periodically.
3. Service Methods
Visual check:
Remove drain plug to drain the fuel when fuel level on the drain pipe reaches 80 % full.
Check connecting hose for damage and looseness.
13-8
To this chapter contents
Flesh air
Fuel vapor separator
Crankcase
13. Emission Control System
Blow-by pipe
Exhaust pipe
Carburetor
Piston
Cylinder
head