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.

Did you take the disc valve apart from the backplate? If so, when you re-assemble the parts, the clearance between the disc and the backplate face must be very tight.
After crashing, there could also be leaks in the system that you cannot easily find.
Consider having the engine serviced by our service dept.

No i didn't take the disc valve off, I tried but it didn't want to come off . It has a tight fit and feels overall ok. O-rings have also been replaced.

Anyway, do you have any ideas what a worn piston/liner can cause? Isn't the regulator somehow linked to the crackcase pressure (which I think wont be normal if there is leaking between piston and cylinder liner)?

Apparently the intake valve has also hit the piston, could the valve be bent or something...? Is the any way to see if it's leaking when closed?

Thanks
Ezanen

Leaking piston rings cause the regulator to get false pulses and make it erratic.

You can check for valve leakage by filling the port with oil and turning the engine through compression.
If the valve hit the piston, it is very likely to be bent.

Ok have to try that oil thing. Thanks for the answers!!!

Good luck!