11U and up will call balks. There is NO balk warning. The umpire should tell the player about the infraction on how not to repeat.
The rule from national is below. Pretty much, if a player squares to bunt, they can NOT take a full swing on that pitch. If a player squares to bunt, they must either pull back or attempt to bunt. Any attempt to hit a ball hard (full swing or slap hit) after squaring is now illegal. This applies to CAL RIPKEN only, which includes Rookies, 9U, 10U, 11U, and 12U. Here's the verbiage from National:
Cal Ripken Division - Fake bunt - slash bunt- a batter is out for illegal action when he player fakes a bunt and then takes a full swing, thus eliminating a player from fake bunting (slap-hitting) the ball. Penalty: Batter is out, the ball is dead, no runners may advance.
SCHEDULING REQUESTS - will be just that...REQUESTS...teams must be prepared to play ANY time on Sunday, even AFTER the schedule is published. We will do our best to accommodate requests and to minimize adjustments after the schedule is published, but any team unable or unwilling to play will be subject to the FORFEIT POLICY
SPRING - A player's age is determined by the Babe Ruth age guideline. If a player is league age 11 according to Babe Ruth, they can play 11U or 12U.
FALL - We move UP in the Fall. A player's age is determined by what their league age is for the upcoming Spring season. If a player is league age 11 in Spring of 2017, they are league age 12 in the Fall of 2017, and are league age 12 for Spring 2018.
Adapted for Fall 2015 and beyond