While you wait for answers, we may have found some information which could help you.
Click here for Briggs Stratton Modelwestwood t1200?
Adding oil to mower ?
my briggs and stratton 3.5hp starts up then cuts out straight away?
lawn mower engine hunting?
How can I fix Mountfield Laser Omega 46 Lawnmower?
McCulloch lawnmower parts removal ?