I am working on a Cub mower which has a Micki carb 698620 and I took it apart and cleaned iit but it still serges. If you hold the throttle with your finger it runs better. I have another enging with that same carburetor on it which does the same. They are a bad design carburetor that briggs used.
Not a bad design, just needs a bit more patience and understanding on how carbs work. They get a bad rap because people don’t have the patience or want to stick the time into properly cleaning and rebuilding. With a little searching there are some good videos on how to clean and rebuild them. Takes about twice as long as a Walbro or Tecumseh carb. Search Nikki carb rebuilding.
Cub Cadet makes thousands of different models. Are we supposed to make a wild guess?
When you post a help request include the product label information off the machine and the engine that is on the unit. The engines are not made by the equipment manufacturer.
These Nikki carburetors are often blamed due to other issues. If you don't understand them, don't tinker with them. Buy a replacement carburetor and keep life simple for yourself.
The gaskets and seals in these are not reuseable as people often think, the rebuild parts cost as much as a new replacement carburetor in most cases.
If this is and engine mounted fuel tank, pull the fuel tank and line. Look for a tiny "pencil" filter where the line joins the tank. This is a creative hiding the filter game that engineers have devised. Within a few mowing seasons and that tiny filter chokes up.
I remove them an replace the fuel line and install a small pancake filter that can be serviced.
