Surging motor on NEW carb!?

l008com said:
So the more I research this online, the more it really does not look like a fuel issue, the more it looks like either some kind of governor issue or an ignition issue.

Assuming that is true, and ignoring the carb for now, what are some ways I can test and diagnose this, other than buying parts. One idea I was told was to put the spark plug tester on there and run it and see if the intensity of the spark in the tester corresponds to the surging of the motor, and that that can indicate a bad coil. I like that and I'll have to try that.

It still surges somewhat when I pull on the governor spring so that suggests the spring isn't the problem. I want to try firmly holding the throttle open more and seeing what happens. Its the governor causing the problem or reacting to the problem.

Aside from the external spring, I'm not sure what I'd even be looking for for a "bad" governor. I assume I'd have to remove the motor and crack it open, which I have done before on a different machine but I really don't want to do now on this machine. I really want the problem to just be the ignition coil so I could just bolt a new one on and be done :D
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Of course it is a fuel issue, or air intake leak. 4 pages of back and forth. You are hunting and surging and running lean on fuel. I have seen this problem hundreds of times.
 
Quite simple. For checking the intake for leaks it is spraying some around the intake manifold while the engine is running. If the engine operation changes then you have an air leakage problem. As narrowing down if carburetor it is called applying a little choke which this engine may not have so that would be hand choking. IF things improves while the engine is running then the problem is in the carburetor.
 
It looks like a Brigg Quantum that was redesigned for OHV head. I think they called it an Intek engine? The long straight fuel lines gives it away. Plus he said he adjusted the valves by a screw. So it must be an OVH. These engines have had issues with starting and running . They never really got it down. I never liked working on them. As it was a converted design from a flat head.

He set the valves for .005. In theory that should be right on. At this point I would leak down test it to make sure there are not air leaks that are untenable. Maybe a head gasket is going.?? If it is burning oil and the rings are worn try a heavier oil.

Since the surging did impove with out really knowing why, it may be a fuel issue. Try putting some seafoam in the gas and run it. I have seen slight surging improve over time with doing that. Good Luck.
 
l008com said:
the more it looks like either some kind of governor issue or an ignition issue.
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Get an open gap style spark tester. Open the gap up and stress the coil out. See how far she can spark. Just recently replaced two of my five mower coils due to weak spark. Only a couple bucks shipped to your door.

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Good idea slomo. People need to understand you need a good ground. Painted or rusted metal may not give you the best ground. Also, this only test the coil. Not the spark plug.
 
So what we know after 5 pages.

Engine smooths out at higher revs. All agree?

Think this carb has no pilot circuit so not guaranteed to run smooth at low revs.

Told OP to set the revs at 3600rpm and see what happens. I was ignored.

Can you drain a full tank into a glass jar, WITH good fat solid fuel flow? Tank cap on? Pull the hose off AT the carb inlet and test this. Probably running on original fuel lines dead internally or the tank outlet nipple full of trash.

Has spark been tested proper with an open gap style tester? Need to stress the coil out. Weak spark will make it run poorly and misfire.

I would do the fuel flow test then check for nice fat blue spark. Might need to test this in low light settings.
 
StarTech said:
Quite simple. For checking the intake for leaks it is spraying some around the intake manifold while the engine is running. If the engine operation changes then you have an air leakage problem. As narrowing down if carburetor it is called applying a little choke which this engine may not have so that would be hand choking. IF things improves while the engine is running then the problem is in the carburetor.
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I've done both of these things and it had zero effect I did the choke on the video I posed, you could see all it did was start to kill the engine.
 
slomo said:
So what we know after 5 pages.

Engine smooths out at higher revs. All agree?

Think this carb has no pilot circuit so not guaranteed to run smooth at low revs.

Told OP to set the revs at 3600rpm and see what happens. I was ignored.

Can you drain a full tank into a glass jar, WITH good fat solid fuel flow? Tank cap on? Pull the hose off AT the carb inlet and test this. Probably running on original fuel lines dead internally or the tank outlet nipple full of trash.

Has spark been tested proper with an open gap style tester? Need to stress the coil out. Weak spark will make it run poorly and misfire.

I would do the fuel flow test then check for nice fat blue spark. Might need to test this in low light settings.
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Engine doesn't smooth out per say. It does get smoother at higher RPMs but it still surges a bit.

OP didn't ignore the suggesting to set the revs to 3600, OP asked how you do that on a carb with no adjustment, and OP was ignored.

I have inadvertantly drained the tank when I took the carb off while the tank was full, the fuel flowed very freely. Also when I swapped the bowl screw/jet, the the bowl emptied and gas flowed through the needle valve very freely. Also the fuel line is brand new, I replaced it at the start of all this.

I did test the spark with a spark plug tester. I don't know the difference between different kinds of testers so I don't know what kind I have? But it was flashing, showing spark. I think I have video of it.

In fact, here is a video of it. It was a sunny day so its kind of hard to see, but it is sparking:
 
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