Yamaha BIG BEAR 250 YFM25BZ Owner's Manual page 35

OFF
1. Arrow mark positioned over "OFF"
With the fuel cock lever in this position, fuel will not
flow. Always turn the fuel cock lever to this position
when the engine is not running.
ON
1. Arrow mark positioned over "ON"
With the fuel cock lever in this position, fuel flows
to the carburetor. Turn the fuel cock lever to this
position when starting the engine and riding.
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