Articles: Lawn Mower Repair

Small engine pistons have three rings,4 cycle engines that is.Lawnmowers, tillers, generators, air compressors and water pumps.The two top rings are compression rings, and the bottom ring is the oil ring and it is usually the one that wears out first,causing your engine to burn oil by not scraping the cylinder clean on the downward stroke,low oil or not changing the oil causes premature wear.Rings come in standard and over size, over size are used for worn cylinders.You can get them in.010,.020 and .030 thousandths over size.Usually standard size rings will work for a rebuild,one shade tree way to tell is to take the cylinder head off of engine,rotate piston all the way up and press your fingertips on piston and try to move it side to side againstcylinder wall, if you have substantial movement then its possible you would need .010 thousandths oversize,to make sure of no oil burning when you put engine back togetherWhen installing piston rings, you must stagger the ring gaps around piston in no certain order, just so no two line up, or otherwise compression and oil will blow by rings so to speak, that goes for all internal combustion engines.A ring compressor must be used to install piston back into cylinder,it will compress the piston rings back into piston enough to tap it back into cylinder, any other way and you risk breaking one of the rings, since they are breakable.To get piston rings for any small engine you will need model numbers from valve cover or flywheel cap, used to be just flywheel cover, but nowadays a lot of the model numbers are located on valve cover on briggs, kohler, tecumseh, honda, kawasaki.Constant white or blue smoke coming from a small engine is a troubleshooting sign of a worn oil ring and continued running in this condition for a season or so will cause the cylinder wall to be scarred,and the the cylinder must be honed to get rid of scarrs to ever stop burning oil even with new piston rings,more expense than worth a lot of times.