http://www.bikeforums.net/search.php?searchid=363159

There are to 'search' buttons. There's one just below the searcj box at the right end of the dark blue bar. Do NOT use that one.
Once in the sub forum like classic&vintage you'll see a 'search forum' button just below all the page numbers. Click that button then advanced search. From there click 'threads started by' and then enter the users name.

search forum<advanced search<user name<switch find posts by user to find threads started by user