How to decide whether to rebuild a carburetor or replace it

Any time you take a carburetor apart to clean or examine it, it's a good idea to replace the gaskets, as well as some other individual parts, depending on the type of carburetor.  For most carburetors, you can buy a rebuild kit which comes with all the standard parts that you'll need.

Rebuild kits often cost around $10 or $15.  If you're comfortable tearing apart and rebuilding your mower's carburetor, $10 or $15 is a very reasonable investment, even coupled with the half hour or so it may take you to clean the carburetor and put it back together.

However, if you're just a casual DIY-er, or if you don't have the time to rebuild a carburetor, you might opt to just purchase a new carb instead.  Prices will vary depending on your model, but in general you can get a new carb for about $30 or $40 for a standard push mower.  Just as one example, a Briggs & Stratton carb rebuild kit for a model 122K00 engine costs $7.79 on Amazon, whereas a whole replacement carburetor would be $29.25.

Installing a new carburetor will take significantly less time than cleaning and rebuilding an old one -- but it may still take a while to do.  You'll probably have to remove the engine shroud, springs and linkages, air filter assembly, and possibly some other parts as well to get the old carb out.  Plus, you'll have to clamp off the fuel line to avoid spilling gas when you remove the carburetor.

If you have the time and you feel comfortable rebuilding the carburetor, that's the cheaper way to go.  You'll just need to buy a rebuild kit and some carb cleaner (if you don't already have some) rather than the whole new carburetor.  But if you'd rather just replace it and be done -- especially if it's an older carb that's already been rebuilt several times -- you won't be breaking the bank.  Either way, the tools you'll need will include a hose clamp and a socket wrench set.  A few rags will be helpful, too.