dont know why my briggs&stratten motor wont start?

You say that you can't get it running. But then you say you must pull it to start it. How else do you start it other than pulling? A recoil rope or kick lever?
Does it have spark? Remove spark plug; hook spark plug wire back on plug. Hold base of plug to head for good ground. Turn crank fast enough to generate spark. Hold it with your hand if you feel brave enough. If no spark, then it may be points, condenser, or coil (if it has points and condenser) Newer models have Magna spark--no points or condenser. There is an "exciter" built in the coil.
Also after cranking, is the plug wet with fuel? If it has air, fuel, and spark at the right timing, it should run.
Another thing is to check to see if flywheel key is in both slots--crank and flywheel. Sometimes the soft key will shear (supposed to so crank or flywheel won't get damaged)
Make sure carb jet (or jets) are clean and open. Won't start if too much or too little fuel. Check for vacuum leaks. May need a valve job ( or valves just cleaned and lapped with compound. But try the easy stuff first.

Robert Brown
August 2008

take out the plug and put a finger over the hole and spin it,there should be enough pressure to blow away you'r finger,if not then suspect the valves.have a habit for sticking open ,if ok then try spraying a small amount of easy start into air intake.if goes then engine and ign are ok and you have fuel prob,if not then its ign or comp.

caine
August 2008