To answer literally your question, there is no limits provided by Yobit afaik. Even on their FAQ you won't see some details about limits.

For your reference, a friend of mine did some BTC4 withdrawal last year. He showed me a 2 withdrawal request of BTC2 each. I don't know if BTC2 is the limit in that case or he just did it on purpose since the second request was placed. The account is not verified although created for years for. Anyways the withdrawal is executed for I think 4 to 5 days upon placing.

But with the replies here, it's obvious that you must not consider using them unless you have some coins currently playing there and you know the risks you are dealing with.