Why does my lawn mower engine rev up and down?

A lawnmower that hunts and surges may be experiencing something as simple as an airflow issue. If the air that the engine requires to run is blocked, especially sporadically, it can cause the engine to slow down. When the blockage moves or clears, the engine may suddenly rev up in response.

Do lawn mowers have timing belts?

You don’t adjust the timing on a lawnmower engine like you do an automobile. The timing gear meshes with the cam gear with a timing mark and that is the only timing there is.

How to set the timing on a lawn mower?

You set the valve timing by lining up the spots on the timing gears when re-assembling the motor,…. its all but foolproof. You set the ignition timing by making SURE the key way and the square key and the slot on the flywheel all line up exactly……again, almost foolproof.

Where is the timing mark on a Briggs and Stratton lawn mower?

Slide the crankshaft into the magneto, or top, side of the engine, leaving the crankshaft gear facing towards you. Be sure the bearing surfaces are clean. Wipe the top cam interface gear with a clean rag. You should see the manufacturers chisel line mark to identify the crankshaft timing mark.

How to set timing on a 4 stroke 1 cylinder engine?

Place a flywheel puller over the flywheel, and hook the puller prongs on the back of the flywheel. Place the puller shaft in the recessed end of the crankshaft, and turn the puller handle clockwise until the flywheel comes off. Inspect the crankshaft key-way for damage, and remove the damaged key. Place a new key in the crankshaft key-way slot.

Where do you find the timing mark on the crankshaft?

Locate and identify the timing mark on the crankshaft counter weight or the camshaft gear. Different model engines will have either of these two locations for the marks regardless of the vertical or horizontal orientation. The crankshaft must be installed into the lower engine cavity first.

How do you set the ignition timing on a lawn mower?

You set the ignition timing by making SURE the key way and the square key and the slot on the flywheel all line up exactly……again, almost foolproof. The embedded magnet (s) in the flywheel pass the induction coil magnet and that charges the coil, and shoots the spark to the plug….

What’s the problem with timing on a lawn mower?

Lawn mower timing is rather unique in the small engine world, which poses some special challenges when troubleshooting an engine that refuses to start. Have you ever accidentally run over something while mowing the lawn? If the object was small enough ( like a small doggie toy) one of two things happen:

What should I do when timing my Briggs and Stratton lawn mower?

Once the engine is timed, the main lower cover may then be positioned and the bolts tightened. The most critical portion of the timing operation is that all of the internal parts must be clean of any foreign debris and oil residue.

What’s the best way to start a riding lawn mower?

Start the mower Go to the carburetor and find the idle adjustment screw, Turn the screw to the left one-half turn. Start the lawn mower. If the idle is still too high, turn the adjustment screw one-eighth turn counterclockwise. If the mower idles too low, turn the adjustment screw one-eighth turn clockwise.