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I have a Kawasaki 24 Hp twin (FR730V) and it uses a Walbro LSF carb. The engine surges badly at all speeds, but only under light to no load. Does it a bit when driving on flat ground and not at all when mowing.

I've cleaned it many times, but no luck. I've removed the welch plug for the pilot needle and it makes no difference where I put it, from all the way in to almost falling out.

Governor is correctly adjusted.

Any ideas on how to clean the pilot system or fix this if it's another problem?

Are the other two Welch plugs still on the top? One larger, one smaller.

And, you are correct. The idle port screw does not do anything. That is why it is sealed off. If you had an air/fuel meter you might see a difference. But not run-ability wise.

I've had this problem for quite a while. Last year I removed the other two plugs to clean the passages. I replaced them with plugs left over from other carb kits. Today I did put my finger over each one to see if there was a change in case one was leaking. No change.

Now that I'm thinking of air leaks, the only things I havn't changed are the gaskets on each end of the carb,

Eggbert said:

I've had this problem for quite a while. Last year I removed the other two plugs to clean the passages. I replaced them with plugs left over from other carb kits. Today I did put my finger over each one to see if there was a change in case one was leaking. No change.

Now that I'm thinking of air leaks, the only things I havn't changed are the gaskets on each end of the carb,

Click to expand...

Step 1: Check for intake air leaks
Step 2: Drill out pilot jet slightly if you know the carburetor is clean.
Step 3: Optional-buy another aftermarket carburetor and see if that fixes hunting/surging, or bite the bullet and buy OEM carb for 3 to 5 times the cost.

Tiger Small Engine said:

Step 1: Check for intake air leaks
Step 2: Drill out pilot jet slightly if you know the carburetor is clean.
Step 3: Optional-buy another aftermarket carburetor and see if that fixes hunting/surging, or bite the bullet and buy OEM carb for 3 to 5 times the cost.

Click to expand...

1: Will do. Maybe even the fuel pump leaking from the pulse line, so will check everything.

2: Don't want to do that as it was fine for 8 years or so without being enlarged. But perhaps there's something restricting things. So maybe clean once again.

3: Have one on order from Amazon.

T-Y all for your responses. An other thoughts are appreciated. Will report back here once the new carb gets here.

How are cleaning the carburetor? Here I use ultrasonics, soap, and water. Carburetor main jet, main nozzle, and pilot screw needs to be remove before cleaning.


Also double check the static governor adjustment.

Yes, it's been in my ultrasonic tank more than a few times, although I use a degreaser vs. soap and water. All those carb parts you mentioned were removed. I was bewildered for a time on how to extract the emulsion tube (as it was stuck) but had it out too.

A few years ago I had trouble with the governor not working. I replaced that star-shaped plastic part that hold the centrifugal balls. A fair amount of work to then find no change. It turned out it was the inner end of the throttle shaft was binding Once I got it cleaned and freed up, it worked fine.

However I will check it again because (and this is where I admit to being a dummy) I didn't realize the governor adjustment screw was left hand thread and stripped the threads. So I re-tapped for a right hand thread, made the adjustment and added a jam nut to the end of the new bolt. I may have added Loctite too. It's been a year or two. Anyway, I did have a look and it seemed tight, but I'll check it again.

Unbelievable. After more than 2 years of this hunting issue, it suddenly went away.... magic! Of course I don't know why or what I did, and it will likely come back, so I'm only ahead temporarily.

I did some fiddling with it today, but nothing worked. But about 5 minutes later I started it and it ran perfectly. Looking back, here's the last few things I did:

1/ Removed the pilot jet needle and spray some penetrating oil down it (it was closer that the can of carb cleaner)
2/ Installed the pilot needle all the way, then slowly backed it out until I thought I detected a slight difference although probably my imagination.
3/ Sprayed WD40 around the carb to manifold intake gasket to see if the rpms would change indicating an air leak.

No change. Still hunting. Turned it off for about 5 or 10 minutes and when I started it again, it ran perfectly.

Engine never really warmed up so sometimes I had to choke it momentarily. Don't have to now although time will tell on that one.

My best guess is the WD40 soaked into the gasket a bit and it swelled cutting off an air leak.

Any thoughts other than abra capocus?

PS: I just remembered something. When I was spraying the WD40 at the carb/manifold gasket, I accidently sprayed some down the intake. As the can was getting low, it was sort of a mist vs. a stream. The engine did spit back a bit, and this happened twice. Maybe this blasted out a bit of dirt all my efforts failed to remove....