Yamaha GRIZZLY 660 YFM660FAT Owner's Manual page 242

If your ATV has stalled or stopped and you believe
you can continue up the hill, restart carefully to
make sure you do not lift the front wheels which
could cause you to lose control. If you are unable
to continue up the hill, dismount the ATV on the
uphill side. Physically turn the ATV around and
then descend the hill.
If you start to roll backwards, DO NOT apply either
brake abruptly. If you are in 2WD, apply only the
front brake. When this ATV is in 4WD or 4WD-
LOCK, all wheels (front and rear) are interconnect-
ed by the drive train. This means that applying ei-
ther the front brake or the rear brake will brake all
wheels. When descending hills, using either brake
lever or the brake pedal will brake the wheels on
the downhill side. Avoid sudden application of ei-
ther the front or rear brake because the wheels on
the uphill side could come off the ground. The ATV
could easily tip over backwards. Apply both the
front and rear brakes gradually, or dismount the
ATV immediately on the uphill side.
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