Technique: This is how you install a new piston in a YZ250
Dirt bikes need a new piston and piston rings every few hours of use. With a two-stroke that is not a difficult job. You can easily do this yourself with minimal technical knowledge and some tools.
In the example you see the replacement on a Yamaha YZ250, but the method is of course the same for every brand. Depending on which machine you have, you may have to disassemble other parts to make the cylinder accessible. The disassembly of the power valve may also be slightly different. It is important to get the correct measurement values from your manual. For example, you need to measure the diameter of the cylinder, the piston and the clearance of the piston rings to know the extent to which wear has occurred.
Immediately after removing the cylinder from the bottom block, make sure to place a clean cloth in the opening. This way you prevent dirt and small parts from getting into your engine block. Always install the new piston and needle bearing with fresh two-stroke oil.
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