titleMaxWidth: Number

Sets the maximum width of title after which it gets wrapped or clipped depending on whether titleWrap is set to true (default) or false.

Default: Automatically calculated based on the length of axis.
Example: 100,200,..

var  chart =  new  CanvasJS.Chart("container",
{
 .
 .
 axisY:{
 title: "axisY Title",
 titleMaxWidth:200
},
 .
});
chart.render();