Step 8: Intake and Exaust valves
There are two valves in a 4 stroke engine. The intake valve which injects the air fuel mix into the combustion chamber, and the exhaust valve which lets out the carbon monoxide and what is left after the combustion. These valves are moved by a cam shaft that turns with the engine at a set time. Sometimes these valves will gather junk around the shaft, and will need to be cleaned by a commercial valve cleaner or by hand. The valve should look very nice and feel smooth in order to work. Sometimes the valves will get scratch and leak oil. This is mostly due to not changing your oil. There is nothing that I know you can do once the valves get this bad, and the only thing you can do is buy new ones. The valve heads can also get chipped and will inject fuel at the wrong time and reduce combustion. Once again if the valves get badly chipped you will have to buy a new valve. To remove the valves you will need to press down the compression springs, and remove the valve spring retainer. Now, putting the valve parts back together again can get a little tricky .You will have to first put the spring and the valve spring retainers back into the engine together. Once you have done this you will have to insert the valve back in place. To place the valve spring retainers back on the Valve you will need to press the valve spring retainers a little bit to the side so you can push the valve into the large hole of the valve spring retainer. Then you will need to press the spring and retainer down so you can lock the valve spring retainer in place. Some valves also have something call a sleeve which you will need to very delicately put on top of the valve and below the valve.