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I have an old Honda GXV 530 on my riding lawn mower. I recently replaced the carburetor, fuel pump, fuel lines, filter, piston rings, intake and exhaust valves (adjusted to specs). Prior to replacing the parts listed above, it was smoking and would only run on full choke. After replacing the parts and cleaning cylinders and pistons, it will crank easily, doesn't smoke and runs well up to half throttle, but once I pass half throttle it requires full choke. Runs smoothly with full choke, but I would rather not have to run with choke. Any suggestions on what to look for or adjust? I have not looked at or adjusted the governor. This model does not have a fuel/air mixture adjustment that I can find. Thank you for your help!

Was that replacement carb an OEM or a aftermarket that they claim will fit, but really doesn't carb.

ILENGINE said:

Was that replacement carb an OEM or a aftermarket that they claim will fit, but really doesn't carb.

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It was an aftermarket I believe, but I cleaned the old carb and put it back on and got the same results. Oh and I forgot to post that I also put 2 new timing belts on as well. Thank you for responding!

Brucepf2 said:

It was an aftermarket I believe, but I cleaned the old carb and put it back on and got the same results. Oh and I forgot to post that I also put 2 new timing belts on as well. Thank you for responding!

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About the only thing you can do at this point is first, check for any air leaks around carburetor and intake manifold. Then, drill out pilot jet until it will run wide open throttle, under load, with no choke. It is a trial and error process, and don’t overdo it. Otherwise, you will have to live with it.

It is being starved for fuel which is why you need to add the choke at 1/2 throttle. Tiger’s suggestion is a good place to start and should quickly identify an air leak if one exists. Beyond that clone carbs are notorious for running lean. Hopefully you have a low and high speed adjustment screw on the new carb. You may want to open the high speed screw 1/4 turn at a time and see if this helps.

Scott_HRR said:

It is being starved for fuel which is why you need to add the choke at 1/2 throttle. Tiger’s suggestion is a good place to start and should quickly identify an air leak if one exists. Beyond that clone carbs are notorious for running lean. Hopefully you have a low and high speed adjustment screw on the new carb. You may want to open the high speed screw 1/4 turn at a time and see if this helps.

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I don’t know if the carb has high and low speed adjustments. I know that this model did not have a fuel to air mixture adjusting screw. I put the old carb back on after a thorough cleaning and it has the exact same results. All gaskets were replaced in carb and intake manifold so I don’t think that there are air leaks. I am wondering if I need to readjust the intake and exhaust valves to a smaller opening. Thank you

Maybe one of these manuals will be of some help.
http://www.ipspower.com/images/docu...buretor-Troubleshooting-Manual-Compressed.pdf

Locate your engine above for correct parts. New Honda OEM Carburetor for $115.00.
If part does not state "OEM Honda" stay away, it's a cheap knockoff.

Replace your carb with an OEM Honda Carb and I’m betting your troubles will disappear. I’ve watched too many Chikanic YouTubes.

It is not the valve adjustment if you did it right the first time. Not the carb either if both carbs have the same issue. It is not getting enough fuel. Is the tank clean? Check the fuel lines for cracks that can suck air, maybe inside the tank if it runs good on a full tank, but falters later. Recheck the fuel filter. Blow through it with your mouth. It should blow easily with no back pressure. If there is any back pressure, replace the filter. You have to blow with your mouth to feel the back pressure. Careful not to get gas in your mouth. Put a piece of fuel line on it if you are worried about the gas.

IT is a governed engine :-
1) the primary jet is blocked / too small
2) the float level is too low
3) the bowl air vent is blocked