why is it backfiring through the carb when starting?

Asa general rule briggs engines are 4 thou inlet, 6 thou exhaust. Set piston 1/4" past TDC to get them right. Is flywheel key intact - if it kicks once and shifts on the key iot will continue to backfire aftewards.

eparkmowers
January 2009

The compression of 74lbs should be fine...!

Tony
January 2009

check the ignition timing it may be out, it may also just be that the carb is too lean, screw in mixture screw and then screw out 1-1/2 turns counterclockwise.
move engine control to run engine at normal operating speed.
turn needle valve in clockwise until engine starts to lose speed (lean mixture).
then slowly turn needle valve out counterclockwise past the point of smoothest operation until engine just begins to run unevenly (rich mixture).
turn needle back clockwise to mid-point (smoothest operation) between rich and lean mixture.
final adjustment of the needle valve should be slightly to the rich side (counterclockwise) of the mid-point.

Tony
January 2009