1986-1991 Kawasaki 650 X-2 Service Manual, Page 37Get this manual
FUEL SYSTEM 219 Fuel Vent Check Valve Inspection
eRemove the check valve and blow through it from each endIJ the check valve will allow air to fllow as shown, it is OKIf aiir will flow through the check valve in both directions or in neither direction, the check valve mustbe replaced
Fuel Vent Check Valve
Fuel Vent Check Valve Mounting
The fuel vent c"eck valve is mounted in the fuel tan ven! hose to prevent fuel from spilling during ridingAir can flow into the tan to aillow fuel to be drawn out by the fuel pump, but fuel cannot flow out the check valveeThe fuel vent check valve must ll!,e mounted so that the arrows on .its case are pointing toward the fuel tan k