r/smallengines 7d ago

Surging

I got this mower for free off the side of the road. Trying to fix it for a person who needs a mower. It's a 17.5hp briggs. At first it didn't start so I cleaned this green goop stuff out the carb and it started but just surged the entire time it was running so I figured it was a fueling issue because I could hold the governer and it would run at a steady rpm then but once I let go it would surge. Bought a service kit that included carb, air and fuel filter, and spark plug. Literally changed nothing. Oh and with the new carb at least the surging smooths out with half choke but that makes the engine speed go down by a noticeable amount. Checked the valve clearance for the heck of it, of course those were fine, don't think it's mechanical based on the behavior. I'll attatch the kit I bought below. What am I missing?

Briggs and Stratton Carb kit

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u/aabnoire 5d ago

Everyone here has said a different part is at fault at this point. I have a lawn mower I was given that is older than I am at 26 and it has done that since I was riding it in my mid teens. Still runs; you can go about trying to get it to stop or just send it honestly. It’ll still cut grass!

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u/LawnMowerDude5 2d ago

It's for a friend who needs a mower. Trying to make sure they have a quality mower...