I guess you are using WCF 4.0.In that you have to find out the tags that are used for configuration.here is a sample of configuration tags that are used in WCF3.0.You can try and look up in the web the same WCF 4.0
<custombinding>
<binding name="LargeCustomBinding">
receiveTimeout="01:00:00"
openTimeout="01:00:00"
closeTimeout="01:00:00"
sendTimeout="01:00:00">
<binarymessageencoding>
maxReadPoolSize="2147483647"
maxSessionSize="2147483647"
maxWritePoolSize="2147483647">
<readerquotas>
maxArrayLength="2147483647"
maxDepth="2147483647"
maxBytesPerRead="2147483647"
maxNameTableCharCount="2147483647"
maxStringContentLength="2147483647" />
</readerquotas></binarymessageencoding>
<httptransport>
maxBufferSize="2147483647"
maxReceivedMessageSize="2147483647"
maxBufferPoolSize="2147483647"/>
</httptransport></binding>
</custombinding>