I'm supposing you are talking about 11g version.
You can set the SyncMaxWaitTime parameter in MBean Browser, from Enterprise Manager.
Click with the right mouse button on soa-infra > SOA Administration > BPEL Properties
In this page follow the link at the page botton to open More BPEL Configuration Properties, to open the MBean browser filtering by oracle.as.soainfra.config:name=bpel,*
In the right pane you will find the SyncMaxWaitTime property.
Please have a look on this page:http://docs.oracle.com/cd/E15523_01/integration.1111/e10224/bp_sync.htm#BABCAGIA