Introduction: Small Engine Manual

Learning how to take apart an engine is valuable information that you can use if something is wrong with someone of yours, for example, a lawnmower.


The materials you will need are:

  • 5/16 in, ½ in, and 10 mm sockets
  • Torque drive- size T20
  • ⅜ in drive extension bar
  • ⅜ in drive ratchet
  • 7/32 allen wrench
  • 10mm combination wrench
  • plastic ziploc bags
  • marker/ sharpie
  • 2 containers
  • oil rags

Step 1: Pulling Off the Air Filter Cover

Unclip the metal clips on the side of the air filter cover. Once you pull off the air filter cover, there should be a green filter as pictured above. The green filter stays on the black hard plastic that it is attached to.

Step 2: Pulling Off the Carburetor Cover

For this step you will need the torque drive and the 10 mm socket with the ⅜ inch drive ratchet. The first thing you need to do is unscrew the little black screws on the right side of the cover. Once you have those screws off, place them in one of the Ziploc bags and label the bag using the marker. After that is done, take the socket and put it on the ratchet. Unscrew the two bolts on the front of the cover. You will have 2 little black screws and 2 gray nuts at the end of this step.

Step 3: Pulling Off the Air Filter

For this step you will need the ½ inch and 10 mm sockets with the ⅜ inch drive ratchet. Removing bolts will be the same as the way you removed them at the last step. The ½ socket will be used for the two bolts in the front while the 10 mm one is used for the bolt in the back. Once you have removed the bolts, put them in another Ziploc bag or the same Ziploc bag you used for the carburetor cover. You will have 2 gray nuts and one gray bolt with a washer (little gray metal circle.)

Step 4: Pulling Off the Carburetor and Gaskets

To remove the carburetor all you have to do is carefully pull the gasket in front of the carburetor off. Then carefully pull the carburetor off. Above there is a photo with a green box. Before pulling off the carburetor, you need look for the spot that is inside the green box. To remove the metal connector you will have to twist the black piece until you can pull the thicker metal connector out. The little metal connector that is connected to the thicker one by a spring needs to be maneuvered out of the hole. The gaskets and black plastic part behind the carburetor also need to be pulled off and put carefully to the side where you will not lose them. At the end of this step you should have 3 gaskets and one black plastic part.

Step 5: Removing the Muffler

To remove the muffler you will need the 10 mm socket and the ⅜ inch drive ratchet. Unscrew either the first lone bolt or the two bolts next to each other. It does not matter as long as you make sure you are holding the muffler so it does not fall when you unscrew the bolts. Once you have unscrewed the bolts you will need to put them in a plastic bag and label it. You will have 3 bolts once the muffler is off.

Step 6: LIfting Off the Gas Tank

Before you get the sockets you need and the wrench, check for gas in the tank. In order to do that you will unscrew the cap at the top and look to see if there is any gas inside. If there is no gas you can get the 10 mm and ½ inch sockets and the ⅜ drive ratchet. Once you have checked for gas and have the sockets and wrench you need, you can start unscrewing the bolts. Use the ½ inch socket for the nuts on the back under the warning label. The two bolts on the sides need the 10 mm socket to remove them. As all the nuts and bolts are being removed you need to put them in a Ziploc bag and label it. After the nuts and bolts are removed you just lift the gas tank off. Make sure after the gas tank is removed that the area underneath looks like the photos above. After the gas tank is lifted off and put to the side, you should have two nuts and two bolts.

Step 7: Unhooking the Wiring

All you need to do for this step is unplug the wires as the photos show.

Step 8: Unbolting the Recoil Shroud

To remove the shroud you will need the 10mm socket, the ⅜ inch drive ratchet, and the ⅜ inch drive extension bar. You will need the extension bar for the two bolts on the bottom side of the shroud. In order to get to those bolts you will have to tilt the engine back and lean in on the crankshaft (the thick metal bar coming out of the opposite side.) After you have unscrewed those bottom bolts make sure you turn the engine back the way it needs to go. The nuts on the top need to be unscrewed too. There will be 2 nuts and 2 bolts once the shroud is pulled off.

Step 9: Unscrewing the Heat Shield

To unscrew the heat shield, you will need the 7/32 Allen key and the 5/16 inch socket with the ratchet. The Allen key is needed for the gray part on top that looks like a hill. The 5/16 socket is for the bolt that is shown in the photo above. The bolts need to be put in a bag and labeled as to not lose them.

Step 10: Unscrewing the Valve Cover

In order to unscrew the valve cover, you will need the 10 mm socket with the ⅜ drive ratchet. Unscrew the bolt in the middle of the cover. After you pull off the cover you will have a gasket and a bolt. Both can stay on the cover.

Step 11: Pulling Off the Engine Head

To pull of the head you need to unscrew the 4 dark bolts on the inside of the head. You will need the 10 mm socket, ⅜ inch drive ratchet and extension bar. Once the head is removed you will have 4 dark gray bolts and a gasket that you will need to put aside in a bag and label it.

Step 12: Pulling Off the Crank Case

Before you unscrew the crankcase cover you will need to check to see if there is oil inside and if there is, you need to drain it. Unscrew one of the two yellow plugs and pull it out. Once you have pulled it out wipe it off and then put it back in. After putting it back in, pull it back out again. If there is nothing on it, you do not need to drain it. Put if there is, you have to unscrew the gray bolt on either side and tilt it so the oil runs out into a drain pan. Once the crankcase is empty, you have to unscrew the 6 bolts on the front. Once you have the bolts off you should put them in one of the Ziploc bags and make sure that it is labeled. In order to pull the case off you have to jiggle it as you pull. Once the case cover is off and all the bolts are in a bag, you should have 6 bolts and a gasket.

Step 13: Pulling Out the Camshaft

To pull the camshaft out, all you need to do is get your fingers around outer edges of the gear and wiggle it out.

Step 14: Unscrewing the Piston

To get the piston out you need a 10 mm combination wrench. You will have to unscrew the two black bolts that are shown in the photo above. You might have to turn the crankshaft in order to get better access to the bolts. Once the bolts are out of the engine place them in a bag. After the bolts have been removed you will have to push the piston out.