Kubota ZG20 / Kohler twin cylinder

[Timbo1959]

I have semi-rebuilt this engine.

REPLACED: Main seal, both coils, intake manifold, rebuilt the crankcase breather, both head gaskets, carburetor, and starter. Compression Checked good and good leakoff.

Starts and runs fine. After about 15 minutes of cutting and sitting there running sounds like it's misfiring or choking. Wish I could attach videos.

Any ideas appreciated.

 

[Mark H_NO]

What have you done with the fuel system? I suspect crud in fuel tank. When engine's not running, it may settle in the tank, so engine starts, and runs until crud builds up on fuel pickup, then engine runs like crap. I'd clean out the tank, pull the pickups and clean, and make sure fuel flows freely from tank to carb. When in doubt, replace fuel lines.

 

[Timbo1959]

It was running fine except for the oil leaks which was the reason I did all the work. I changed the fuel lines, the fuel filter, and oil cooler lines.
If you look at the second video you can see the throttle / choke cables moving.
Do you think fuel restriction can cause that?

 

[Mark H_NO]

I don't see any videos. My opinion on the fuel tank comes from it running well for 15 minutes, then missing. Coils can also heat up and cause problems, but you did say you replaced them. Where did the coils come from?