The easiest ways to do this are to slice, or split by period.
outFile = r"C:\GIS\output\" + lname[:-4] + ".pdf"
# OR
outFile = r"C:\GIS\output\" + lname.split('.')[0] + ".pdf"
Also, you do not need to have the double backslash when you use the r'' (raw string method)EDIT: Sorry, I just realized I had a typo in here. The colon was supposed to be before the -4 to get everything before the period in the path name.It would be best to use one of the two methods above. Sometimes, for some reason, when you try to use strip or rstrip() it will cut off an extra character. For example:
>>> test = r'C:\Users\Caleb\Desktop\EucDistTools\ascii\polys.shp'
>>> print test.rstrip('.shp')
C:\Users\Caleb\Desktop\EucDistTools\ascii\poly
>>>
The above was done in the interactive window of Python. See where it cut off the "s" in polys? This is why it is better to use split or slicing. Another method is the os.path.splitext().
>>> import os
>>> print os.path.splitext(test)[0] # 0 index to grab everything before the period
C:\Users\Caleb\Desktop\EucDistTools\ascii\polys