The title of the search result is always getting limited to some characters. And it is limited by the display templates under Gallery section. "Item_CommonItem_Body.html". And the maximum no of characters is set by the field maxTitleLengthInChars.
The code corresponds to that is shown below:
var titleHtml = String.format('<a clicktype="{0}" id="{1}" href="{2}" class="ms-srch-item-link" title="{3}" onfocus="{4}" {5}>{6}</a>', $htmlEncode(clickType), $htmlEncode(id + Srch.U.Ids.titleLink), $urlHtmlEncode(url), $htmlEncode(ctx.CurrentItem.Title), showHoverPanelCallback, appAttribs, Srch.U.trimTitle(title, maxTitleLengthInChars, termsToUse));
So in order to show the entire title ,the code has to be tweaked like
clicktype="{0}" id="{1}" href="{2}" class="ms-srch-item-link" title="{3}" onfocus="{4}" {5}>{6}</a>', $htmlEncode(clickType), $htmlEncode(id + Srch.U.Ids.titleLink), $urlHtmlEncode(url), $htmlEncode(ctx.CurrentItem.Title), showHoverPanelCallback, appAttribs, title);
See the highlighted portion where trimming is removed based on maxTitleLengthInChars.