Air filter and/or fuel filter may be clogged; carburetor needle valve(s) and/or linkage may need adjustment. You may have an exhaust valve that is leaking or your head(heads) needs to be decarboned another check if you have a point style ignition, clean and regap the points
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briggs and straton, kohler, or kawasaki, depending on the model
The Briggs and Straton Quattro is a 4 hp engine
The Briggs and Straton Quattro is a 4 HP
100 inch/pounds
Timing is off ...
.002-.005 intake and, .005-.007 exhaust
It just unscrews from the motor
it will hold about a half quart of oil
B&S site
Is it an OHV engine? If so they would be loctaed above the piston head on your mower.