Hello,
is that a few weeks on a www.bicitime.com site, done in joomla 3.4.8 Stable.
On k2 inseriscon plugin if a new item does not save me the text because there is the quotation mark.
The problem is with I can get on top of this thing, I also tried reinstalling k2.
You have tips?

Hello,

Quotation marks work fine, tested with the newest K2 version under J! 3.6.2.
imgur.com/a/I8zQb

If you are using 3rd party K2 extensions, try disabling them temporarily in order to find the culprit.