engine tuning help?
I have a ZDZ 40RV That I can't seem to get to run right.
Two problems. The first is the idle is very sensitive. It will idle high and then drop off suddenly to a very slow idle. I can't get the thing to run in between. I have adjusted the carburetor leaner and richer, even switched out the carburetor with a new one and it still behaves the same way. I then adjusted the timing and changed the spark plug and gapped it to specs. Still could not get the engine to idle right.
The second problem is when the engine is up to full rpms, when I cut the throttle the engine dies abruptly. If I reduce the rpms slowly the engine will remain running.
The engine is a newer engine, producing good power, transitions well from idle to full rpms, and compression is okay.
I have fresh fuel, checked the cylinder base gasket, adjusted the timing, and changed carburetor with one off of a good running engine.
I'm not sure where to go from here. The only other things I can think of is the rotary valve or ignition.
Where should I go from here?
Thanks