I think some call it hunting. The motor, even under no load, at full throttle... it perpetually changes rpms like twice per second. Kinda like it revs up and down with a fast rhythm. I put a new carb (Amazon) on my Countyline 25ton and it ran fine for a few days but now this. It also isn't as strong splitting an oak round, it bogs down under load. I think there is a jet under a screw on this carb? I unscrewed it and I see a hole there, maybe there is a jet in there? What could I insert in there to 'ream' out any crud to open it up or should I do something different? Kohler 265 6.5hp motor. The splitter is functioning, it's just not normal and the sound is kind of aggravating. The first problem I had with this, I fixed it, the throttle/governor linkage was not attached securely. Lastly, the gaskets that came with this carb are cheap and one broke before I even got it installed. I put it in anyway. Would this cause problems like this? Is there a good brand of gaskets?
Sounds like you got a junk carb. What was wrong with the original? The hunting is a lean condition while the carb is on the idle circuit for fuel delivery. Or an air leak downstream of the throttle blade. Bad gaskets, cracked intake, incorrectly adjusted idle circuit, or a partially plugged idle circuit are all typical causes. If it's not as powerful under load, that may suggest the new carb has a smaller venturi, or may also have issues delivering the correct amount of fuel under load, from the main circuit.
You can cut your own gaskets if you can't find one . If your going to one off the gasket it may be cheaper to buy it but if you have the paper or cork just cut one.....but I'm guessing if your asking about gaskets you don't cut your own.
A quick way to sort linkage/governor issues on a surging engine, is to hold the throttle still, then move it slowly. If it runs fine from idle on up to full speed, the issue is in the governor and/or linkage. (rare) If it sputters or stalls, then the issue is in the fuel delivery or intake system. (typical)