If you mean the engine will rev up and down as it is running, it has been my experience that a dirty air filter is a cause of the fluctuation.
Buy a lawn mower engine repair manual at Border's or Barnes & Noble.
A 5hp craftsman engine has a compresson of 135psi
There should be a sticker/stamp an the engine somewhere. It will give you a few specifications about the mower.
Symptoms of a bad ignition coil on a lawn mower include difficulty starting the engine, engine misfiring or stalling, and poor performance or loss of power while mowing.
very gently, or the mower will get squashed
depends on the engine but it will be on the engine block.
The sound of a jet engine vibrates more than the sound of a lawn mower.
from a distance away why does a jet sound loader than a lawn mower
The pull cord of a lawn mower is used to manually crank the engine to get it started. As the engine is quickly turned, a spark is created which begins combustion.
A lawn mower works by converting chemical energy (energy stored in the gas) to mechanical energy.
Check the underneath of lawn mower for grass built up.
You can find the operator's manual for that engine at www.briggsandstratton.com. You will need to contact the manufacturer of the mower for the lawn mower owner's manual. Briggs and Stratton did not amke that mower, only the engine.