Tune-up your lawnmower.

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Last Update 07/08/08

How to Tune-Up Your Lawn Mower

By following these simple steps you can bring your lawn mower's engine back to life and keep your mower running stronger, longer.

Begin by starting the engine on your lawn mower and running it until warm and the fuel tank is empty.

Disconnect the spark plug wire to prevent the lawn mower from starting accidentally.

Change the Oil

Clean around the oil fill and remove the dipstick. Depending on your type of machine, the oil may be drained by removing an Oil Drain Plug located under the mower housing just above the blade. To get to it, put your lawn mower up on a couple of cinderblocks. Then, with a basin to catch the used oil, remove the plug and allow the oil to drain until it stops dripping out of the mower.

Put the Oil Drain Plug back in then refill the engine with oil. Use the Oil Dip Stick as a guide and only add oil up to the "Full" mark on the dipstick. Oil capacity is approximately 20 ounces on most lawnmower engines.

Change the Spark Plug

Take the lawn mower off the blocks and remove the spark plug. Before check its gap (refer to your owners manual for specifications), most Briggs & Stratton engines require a spark plug gap of 0.030" or 0.75mm. After checking the gap, screw the new spark plug in finger tight then tighten 1/4 to 1/3 turn more with your socket, but do not put the spark plug wire back on just yet!

Replace the Air Filter

Now you may take out the old air filter and replace it with the new one. A new high efficiency air filter helps your lawn mower's engine perform at its peak. Be sure to saturate new foam filters with fresh engine oil, wrap in a clean cloth, and squeeze to remove the excess oil before installing. If you have a Cartridge air filter (as illustrated, right), skip this step.

Check and Replace the Blade

If your lawn mower blade is chipped, dented, bent, cracked or dull now is an excellent time to replace it.

A study at the University of Nebraska proves that gas-powered mowers with sharp blades use roughly 20-percent less fuel than mowers with dull blades. Plus, sharp blades slice grass tips cleanly so your lawn looks better and is less susceptible to disease.

Be sure the Spark Plug Wire is disconnected then tip your lawn mower on its side.

Use a piece of wood to block the blade and keep it from rotating while you work to remove it. An old blade may have jagged edges that can cut you if you are not careful so be sure to wear gloves when handling it to protect your hands. It also would be a good idea to keep the gloves on when handling the new blade since it definitely will be sharp.

Remove the bolt that holds the old blade. Mount the new blade with the curved edges toward the housing. If the blade is installed wrong it will not cut correctly and may cause an accident.

Fasten the new blade using the original washers and bolt. Tighten the bolt that holds the blade to a torque of 60 ft-lb / 82 N-m (set your torque wrench to sixty pounds then tightened the bolt one click. Do not click it again as you eventually will ruin your torque wrench if you continue to give "just one more click to be sure"). Check the torque settings in your owner's manual to be sure of the correct tightness and always position the curved ends of the blade to point toward the lawn mower housing.

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