I inherited an LX178 that has been sitting around for a few years with gas in the tank, hoses, etc. I cleaned out the tank, blew out the lines and installed a new fuel filter. Put in fresh fuel. I got it running and at high RPM's it seems to run OK. At low RPM's, the engine surges, if you lower the RPM's to much, it just dies. You can see the govenor moving back and forth. Is there a way to tell if it is the govenor is bad or is this a case where the carburetor just needs a good cleaning and/or a carburetor kit installed ? I have not taken the carburetor off yet. I called the local JD dealer and he says he cannot find a kit for it anymore, nor a gasket set. Anyone have a part number and a source for a carburator kit? It has the Kawasaki 14hp engine.
Your LX will have a low speed air adjustment needle. It is towards the engine on the carb. It probably still has the limiter cap on it but when you remove it you can adjust the low speed mixture and this might cure your problem. If it was governor related it would continue at all RPMs. It is very likely that the carb needs cleaned. As far as a kit you probably only need the bowl gasket(9) and possibly the bowl nut gasket(14) since it may have been compressed(its brass). It is also very likely that it is only the pilot jet(1) that is in need of some cleaning. The small openings on it can easily become varnished. The numbers I put in () are on the parts illustration I have attached.
I first took off the carburetor and cleaned it. It was a mess inside since the mower had sat idle for a few years with gas in it. When I got it back together, surging was still there. I then tried to tweek the adjustment you spoke of. It does still have the limiter cap on it. I tweeked it about a half turn both directions. First, ccw and it seemed to have no effect. I tweeked it cw and I started getting blue smoke out the muffler, but yet the surging was still there in both cases. When I shut it off, I now noticed I have gas dripping out of the vent tube, so I think I did more damage than good when I cleaned it. Would the old gas idle time have possibly caused the fuel pump to get gunked up causing this surging?
I will try to take the carburetor off again tonight and clean it again. Any ideas on why I now have a couple table spoons of fuel coming out the vent tube after it is shut off? Like maybe I did not get the needle valve cleaned good or something? And I am not impressed with the design idea that I have a hot muffler directly below the leaky carb....
Yeah the LX178/188 had their fair share of engine fires. There is an upgraded fuel pump to address the issue. Gas from the carb sounds like the float is sticking or like you said dirt on the needle valve. Bad news on these carbs is the seat is not replaceable so if you can't fix it by cleaning you have to buy a new carb.
Surging can also come from some slop in the throttle linkage. I attached the procedure to adjust the cables and governor maybe that will help. Good luck I put a new carb on my LX188 and it still won't run right and that is not a cheap fix