Set Max 85 Char in Xsl Substring

I want to set the char length max 50 Char more then 50 char should be not visible and make sure string willn't terminate in between the sentence/word

<xsl:value-of select="substring($bodyContent, 1, 85 + string-length(substring-before(substring($bodyContent, 86), ' ')))" disable-output-escaping="yes"/>