My 12.5 hp B&S willnot runafter winter it is backfireing through the Carby & air filter

Have you hit anything with it? As in something got caught and stopped it dead in its tracks?

Did you use a fuel stabilizer?

No I have not hit any thing hard to stop it and I have put fresh petrol in the tank

Yes but when it was setting, was it run with stabilized gas in it...

It sounds as though you need to clean the carb...

OK WILL clean carby & give it a go thanks

my 12.5 hp B&S willnot runafter winter it is backfireing through the Carby & air filter
Turn crank by hand and feel for compression the intake valve is proably stuck in the open position. Free it up; and it will be ok

Substitute the coil and see if this won't solve the problem.

I would suspect that the carb has water or other contaminents. Remove the carb bowl and inspect. Clean as needed. Also drain the tank and replace the fuel filter if you find anything foreign in the carb bowl.

I have a 17 horse briggs that's been in storage,it has a overhead valve system,it to backfifes through the carb,I cleaned carb and freash gas,hot do I check to see if the valves are stuck,thanks