Hello

I have a crashed 140DZ that doesn't want to idle at all. Engine was disassembled and cleaned entirely after the crash and damaged parts were replaced. The pump and the regulator seems to be working properly now, but for some reason the engine doesn't run properly under about 4000 rpm. It seems to get so rich that it starts to "detonate" (right word?) and quits if more throttle isn't applied. Over that 4000 rpm the engine runs just right and seems to give normal power.

Regulator screw is also far off to the lean from the usual position. With the screw in the normal pre-crash position the engine runs really rich.

I was wondering what kind of an effect does a worn piston have on this type of engine/regulator, could it create that kind of mixture variations? I'm not sure if the piston is worn anyway.