From:Dave Hennessey
Subject:Early 1929 - set-screw exhaust Date:Sat Feb 22 00:07:27 2014
Early 1929 KJ exhaust systems were attached to the cylinders by "set-screws" in the cylinders rather than by the "big nuts" on the pipes of later-1929, 1930 and 1931.

But I've never seen one.

Does anyone have a bike with set-screw exhaust? Or cylinders with the tapped holes for same?