I have a D4-5T that I "saved" and I noticed that the pony motor does not have a governor on it. Also, the pony motor does not seem to be able to maintain RPM when the main engine is set from start to run even at full throttle. The pony starts on the first or second pull and sounds fine.
Were there models of D4 ponys that did not have a governor?
I checked the throttle plate and it is open all the way, so I am wondering why the pony will not maintain RPMs then the main is turning under compression.
C. D. Hunter