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650 briggs starts and runs fine but after it warms up it starts surging up and down.I replaced the carb but still doing the same thing.

chugalug1299 said:

650 briggs starts and runs fine but after it warms up it starts surging up and down.I replaced the carb but still doing the same thing.

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I guess since i have not got a reply nobody know what i might try to fix my problem.

Newer engines are jetted lean, they will "hunt" usually with no load..The newer ones have little or no adjustments, without any equipment model/type numbers off of the engine and the numbers off of whatever equipment this is on, one really cannot say a whole lot.....

Fish said:

Newer engines are jetted lean, they will "hunt" usually with no load..The newer ones have little or no adjustments, without any equipment model/type numbers off of the engine and the numbers off of whatever equipment this is on, one really cannot say a whole lot.....

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Its on a swisher wheeled trimmer number on motor is 124t02-0129-b1.It started surging changed plug and filter that didn't help.Checked carb and didn't find no trash in bowl so went ahead and bought new carb changer gasket and oring.But still doing same thing.When it first starts runs fine but when it starts getting warm starts surging.Also checked tube where it hooks on to intake on block all looks good im stumped.

May be running a little too lean. Just as a test, try appling a little bit of choke to see if it smooths out. gregjo1948

Carb running lean is the most common problem, but can also be caused by governors springs out of sync on the two spring setups, as well as attempting to overspeed the engine.

ILENGINE said:

Carb running lean is the most common problem, but can also be caused by governors springs out of sync on the two spring setups, as well as attempting to overspeed the engine.

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There is no adjustment screws on carb and on the governor there is no extra holes to change spring tension.This carb don't have a choke it has the primer bulb on the inner air filter case.

On briggs they engine speed is adjusted at the governor by bending the metal tab that the spring is attached to. On the two spring setup, if they get out of sync will cause a surge, as well as trying to run the engine faster than the carb can supply fuel.

ILENGINE said:

On briggs they engine speed is adjusted at the governor by bending the metal tab that the spring is attached to. On the two spring setup, if they get out of sync will cause a surge, as well as trying to run the engine faster than the carb can supply fuel.

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That worked thanks for all the help.