How does the lawn mower engine get lubed?

Question

And why does black dust or carbon come out of my muffler when i take it off. Briggs & Stratton engine 6.25 hp

Answer 1

Small 4 cycle engines are oiled by what's called splash lubrication. The oil sits in a pan at the bottom of the engine and is stirred and splashed by the crankshaft up onto the valves and piston rings after which it falls back into the pan to repeat the cycle. As far as black dust coming out of your muffler, I would say that its the result of a too rich fuel/air mixture resulting in deposits. Remember, black smoke in your exhaust means that your fuel/air mixture is too rich. Blue smoke means that oil is getting past your piston rings to be burned along with the gas. Only 2 cycle engines have oil mixed in with the gasoline.

Answer 2

It may also be rust as mowers don't get used everyday ( except commercial use ones) The Briggs engine uses a small extension on the connecting rod to splash oil about so it has no oil pump

Answer 3

90% of the basic lawnmower/lawntractor motors are of a 'splash' variety - meaning when the motor rotates - it literally throws oil around to lubricate the vital berings. The highest a basic motor can rev is 3600 rpms - any higher and it will destroy the motor ( the berings werent designed to withstand high horsepower - aftermarket /machining would be needed to attain higher horsepower).
Blue/black smoke is excess fuel unburned - meaning its running too rich - adjusting the carb will solve that. Sometimes a little black 'soot' is normal ( most my engines have it and i tuned them properly) .
White smoke is burning oil.

Answer 4

Oil is mixed in with the Gasoline.