Hey John. I had the same problem with my OS-91 four stroke on my H9 P-51. The fuel would just run like crazy into the carb. I put a Cline regulator on mine and it took care of it. Check out
http://www.billsroom.com/pcfs/ for the info.
ORIGINAL: JohnMcGowan
anyone got any ideas about the OS 120 problem? (see previous post by me/) thanks!!
John