Delete all not allowed characters..

[Abandoned]

Hi..
I want to delete all now allowed characters in my text.
I use this function:

def clear(s1=""):
    if s1:
        allowed =
[u'+',u'0',u'1',u'2',u'3',u'4',u'5',u'6',u'7',u'8',u'9',u' ', u'Ş',
u'ş', u'Ö', u'ö', u'Ü', u'ü', u'Ç', u'ç', u'İ', u'ı', u'Ğ', u'ğ', 'A',
'C', 'B', 'E', 'D', 'G', 'F', 'I', 'H', 'K', 'J', 'M', 'L', 'O', 'N',
'Q', 'P', 'S', 'R', 'U', 'T', 'W', 'V', 'Y', 'X', 'Z', 'a', 'c', 'b',
'e', 'd', 'g', 'f', 'i', 'h', 'k', 'j', 'm', 'l', 'o', 'n', 'q', 'p',
's', 'r', 'u', 't', 'w', 'v', 'y', 'x', 'z']
        s1 = "".join(ch for ch in s1 if ch in allowed)
        return s1

....And my problem this function replace the character to "" but i
want to " "
for example:
input: Exam%^^ple
output: Exam   ple
I want to this output but in my code output "Example"
How can i do quickly because the text is very long..