I have a tractor and when it gets hot it revs really high but when it is cold it revs normally

SOURCE: Huskee 25 hp lawn tractor with briggs & stratton motor wont start

Most all manufacturers have the Users Manuel available on line you will need the Make and Model to pick the correct one. Have you replaced the battery. It can show the correct voltage but have no cranking amps. I believe if the solenoid is trying to engage the Dead Man switches are closed. With the starter disconnected from all power sources do the teeth on the starter turn or are they locked up? If they refuse to move do you have an Auto Zone around or another parts store or electrical engine repair store that can test the starter. Make sure the mowing deck is not engaged while you are trying to start the engine. I hope these rudimentary suggestions help.

SOURCE: lawn mower stalls when engine is hot

first thing is to check that plug is not fowling up when hot due to motor burning to much oil.

SOURCE: Craftsman LT 1000 with Briggs and Stratton 20 OHV

lift your seat and look at the label that you got your model number from. to the right of the model number is the serial number. the first six digits of the serial number is the date your tractor was made - for example: serial no. 060802D002756 would make the unit made June 8, 2002

SOURCE: craftsman 19.5 lawn tractor w/briggs & stratton keeps flooding

This could be a number or items from no spark to a faulty carburetor, a plugged up air filter, valves out of adjustment, poor gas, faulty spark plug.

First, see if your getting spark, how about taking the wire off a plug(s) and holding it about 1/8" or so away from the plug with some masking tape while you crank the engine. You should be able to see the spark jumping the gap, it helps if it is not too light outside. If you attempt to do this with your hands, you will get a spark jolt, it hurts, so use the tape and remember, the engine could start so proceed with caution.
If you have no spark there, then you ignition or magneto is faulty. This would be unlikely in the broader scope of things. You will likely get spark. Make sure the plug is clean, take it out and inspect. If it is covered in gunk well clean it. It will smell like raw gas but you already know that. Change the plug if in doubt.

Remove and clean and replace the air filter.

If you have spark, and a clean filter it is likely a carburetor problem, Depending on the carb, it could be the choke is faulty or, as per the below.

Depending on what model you have there is a float assembly in the carburetor that stops the fuel from flooding the carb and air intake. The gas tank is higher then the carb right, so if you dont have a mechanism for stopping the fuel from leaking out the hole that goes into the engine, it will all leak out right, as into the fresh air intake because its easier than going into the engine. So, there is a miniature float assembly, sort of like your bathroom toilet float to stop the water. Well there is a small wedge type needle that seats into a hole and it is attached to a float. As the gas rises in the bowl, it pushes up the float, sealing the gas into a chamber, as you use more gas, the float lowers and more gas goes in. So ,there is dirt jammed into the float bowl sealing needle, just a little, thats all it takes. So, shut off the gas somehow, hopefully you have a valve, or squeeze the rubber line, then undo the float chamber, its one nut on the bottom. Clean carefully. The needle, little spring and float assembly are delicate. Also, the needle could be worn from engine vibration, so it may need a new needle. It would help if you described the engine and carb though.

I posted that as a solution to another problem, but yours may also be the valves need adjusting. Depending on the amount of hours, say over 200, then the valves timing will likely be off a bit. Check the clearances with a feeler gauge, it is not as difficult as it seems. Check your Owners manual for the clearance at top dead center. TDC is when you take the plug out and watch the piston arrive at the top of the cylinder through the spark plug hole when you are turning the engine over (do this by hand, battery off. Make the adjustments with the valve cover off. Follow the instructions.

Hope some of this helps.

SOURCE: timing for briggs and stratton 15.5 engine

There are no timing marks, timing is correct when the flywheel key is in place, the flywheel is properly torqued and the air gap for the magneto is properly set