little help on a briggs and stratton i think clasic 35 mower

heres a qundry for you engine that has fuel and spark but does not run

i had given to me a mountfield mower that was not running is a bit of a sorry state needing a cable for the stop bar
and in need of a good clean carb and tank as it was i think hanging around for a while

its got spark as i got a inline spark tester and its got fuel as it smells and is wet when i take out the plug

any ideas on what wrong