B & S V-Twin 656cc Hunting

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Diwali

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My JD X127 engine, B & S V-Twin 656cc, model 40N8770072B5 runs but is continuously hunting After removing the air filter and spraying the intake with carb spray the engine runs smoothly for a few seconds and then starts hunting again. Same happens when a little choke is applied. If I rev up the engine holding the governor lever it runs fine but when released it is hunting again.
Checked and cleaned plugs; replaced the fuel filter and checked fuel pump flow. I'm a bit hesitant to tackle the carb - the machine is less than 2 years old. But now at a loss as to the next steps to solve this.
All suggestions gratefully received!
 
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Auto Doc's

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The carburetor bowl should not be too difficult to get off to see if it has any rust or water droplets in it. A carburetor will not suck in water droplets, but it will interfere with proper fuel flow into the main jet.

A fuel can that sits open will collect moisture from the air.
 
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Diwali

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Auto Doc's said:
The carburetor bowl should not be too difficult to get off to see if it has any rust or water droplets in it. A carburetor will not suck in water droplets, but it will interfere with proper fuel flow into the main jet.

A fuel can that sits open will collect moisture from the air.
Click to expand...
Thanks. Removing the carb bowl turned out to be a bigger job than expected…. and, after cleaning, it didn’t fix the problem! I should have done a full carb service while it was in pieces. ☹️
 
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Auto Doc's

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Hi Diwali,

Sometimes it's a matter of trying the simple approach first.

Yes, most likely the carburetor will need some disassembly to access the fine passages that are clogged. Do not remove the plate with screws because it will have to be recentered if messed with.

Here is a parts link that may help:
www.partstree.com

PartsTree - Home of OEM Parts for Outdoor Power Equipment

Parts lookup and repair parts diagrams for outdoor equipment like Toro mowers, Cub Cadet tractors, Husqvarna chainsaws, Echo trimmers, Briggs engines, etc.
www.partstree.com www.partstree.com
 
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slomo

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Auto Doc's said:
A fuel can that sits open will collect moisture from the air.
Click to expand...
+1

As well as dirt, bugs, grass and all other junk you don't want in your carb.

All you guys using open top fuel cans better get a new EPA sealed pain in the rump spout. Better flush out your can or all that gunk will be heading towards your carb.

Briggs makes a good can and spout.

www.homedepot.com

Briggs & Stratton Smart-Fill Replacement Spout 85040 - The Home Depot

Visit The Home Depot to buy Briggs & Stratton Smart-Fill Replacement Spout T205C
www.homedepot.com

1747151067003.png
 
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slomo

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This is a good can too.

1747151550356.jpeg
 
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Diwali

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Thanks for all the replies. All useful.
Had another go with the carb. and cannot get the float assembly out of the carb bowl. It’s stuck solid. How do I get it out to check and clean without causing damage?
 
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Auto Doc's

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Hi Diwali,

Is the pin stuck where the float hinges to open and close the needle. Some of the pins only fit one direction and wedge in place.

You may need to use a small pin punch but be careful because the aluminum where the pin goes is fragile and will break if too much force is used.

If you are not familiar with working on carburetors, you might better off buying a replacement off of Ebay. I am not a fan of Amazon due to problems with some of the products.
 
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