howcan I fix my briggs&straton push yardmachine 4.5HP engine no spark?

Try this... Remove the cover from the flywheel (the pull start cover) and check for rust on the magnetic segments on the flywheel. If you find rust, take a piece of fine emery paper and gently clean the surface. The next step is to check for any buildup of oil and dust between the legs of the magneto coil and the surface of the flywheel. I recommend using a steel feeler gauge of about .006mm or one that will fit the gap with a little space to spare. Using a cutting motion move the feeler gauge through the gap to remove any dirt and providing the coil is ok you should get a good spark once you have replaced the cover that you removed earlier.

Mower Man
May 2007