Briggs 625EXI rpm surging

slomo

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Typically I would suggest exactly the same thing, it is the cause of probably 75% of surging problems, but I believe these carbs do not have a low speed circuit. There is a plastic piece for an idle fuel pickup in the carb and a cast depression for a welch plug on the side like an emulsion well, but it isn't drilled out. Seems like briggs added it as an afterthought if they wanted to add an idle circuit.
Think these are fixed rpm engines as in 3600 or 0. No need for a pilot jet with a primer.
 

slomo

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I use a pump spay bottle with soapy water for finding vacuum leaks. Cheap and in every kitchen cabinet. Doesn't have to be flammable.

That soapy water trick is also great for finding bad plug wires on cars and trucks ect....
 

XGamer223

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Hi everyone, sorry for later answer.
Thanks everyone for their answers!
Thankfully, I think it was (once-again) the dirty carb, atleast for now - it works (as much as the bad carb design allows it to).

I opened it up again, cleaned it throughout, completely took apart the white "cartridge", gave it a nice clean. After that, it runs okay. Only time it stutters is when you just start it up, but for like 3-4 seconds, once or twice, but then the RPM even out. It again starts to drop and rise RPM when it gets hot, but it isn't even close as it used to be. It runs fine even with the breather tube on.

I really feared it was a vacuum leak on the gaskets, as some of you suggested. Thankfully, they're okay (I really expected them to be bad since the process of opening the carb itself may damage the bowl one). Since no parts available in my country for this specific carb, I'm glad they're fine.

Also, someone filled double the oil than it should've been. I brought it down to a normal level.

I stil don't know how it runs under load, as grass stopped growing.
Here's a video preview of how it sounds now, not perfect (turn sound on)... but atleast it runs! Thanks everyone for your help, I really appreciate it.
 

slomo

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Keep cleaning on the carb. Might take 3 or more cleanings to get her to run correct.

Far as the gaskets go, I put a film of 100% silicone grease on all sealing gaskets. Carb bowl, carb to intake and so on. This moisturizes them and aids in removal if needed. Keeps the gasket sticking slash tearing way down to zero.
 

XGamer223

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Keep cleaning on the carb. Might take 3 or more cleanings to get her to run correct.

Far as the gaskets go, I put a film of 100% silicone grease on all sealing gaskets. Carb bowl, carb to intake and so on. This moisturizes them and aids in removal if needed. Keeps the gasket sticking slash tearing way down to zero.
Thanks for the tip! For now it's "fine". I don't really expect much from it anymore.
 
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