Starting version 10.1.3.4, to set time out in seconds for a partner link, it is just configuration in bpel.xml.
E.g. the configuration below sets the timeout to 5 seconds
If the WebService is on the SAME host as the BPEL, it is also necessary to set the property "optSoapShortcut" to FALSE. The parameter "optSoapShortcut" is by Default = TRUE. It should be set to FALSE to force local SOAP request to go through SOAP instead of internal calls.
The parameter Timeout is documented in : Oracle® BPEL Process Manager Developer’s Guide
optSoapShortcut is documented in : http://download.oracle.com/docs/cd/B31017_01/core.1013/b28942/tuning_bpel.htm#sthref496