Questionben, bought a used 24 horse honda gx670 that powers a mud motor. at wide open throttle, it seems to run fine. at idle and lower rpm's engine seems to surge and then settle, surge and settle, and so on. i have little or no experience with small motors. would this be something with the fuel line or carb? spark plugs? thanks in advance for your help!
AnswerMatt
Problem: Engine idles roughly, unevenly, or surges.
Possible causes:
1. Carburetor is dirty.
2. Air leak in carburetor or intake manifold (e.g., bad O-ring, gasket, primer).
3. Carburetor is improperly adjusted or needs service.
Surging is an indication of a blocked idle or intermediate passage. A foreign object is blocking or restricting a passage. Possibly a piece of trash got left in a passage and has probably hardened. It is just a matter of getting it out and may be impossible to do so.
Here is what I would do if I were working on it:
I came across an aerosol carburetor cleaner that changed my opinion of spray cleaners. This is a cleaner sold by at Auto Zone parts stores. It is an Auto Zone brand “Valucraft Carb Cleaner” Part Number: AZ-4, 13 ounces in a yellow and black aerosol can with a red plastic cap. It for around $2.50 per can. I have been very successful in cleaning carburetors often without removing them from the engine. I have not had many carburetors I could not clean. Sometimes I use the entire can. At the price it sells for, so what.
WARNING - Do not get “Valucraft Carb Cleaner” in your eyes or on your skin. Use a full-face shield for eye and face protection. Wear protective gloves. The cleaner will damage rubber so remove rubber carburetor parts to prevent damage.
Valucraft Carb Cleaner will melt and wash away varnish. Spray as much cleaner as possible into the idle and intermediate passage. Follow by blowing out with compressed air. If this doesn’t work you may try disassembly and immersion cleaning again. Be sure to blow passages and everything else out after cleaning.
