To achieve the desired compression ratio, you will need to use shims, which are mounted between the cylinder and the crankcase or between the cylinder head and the cylinder.
You can stack rings of different thicknesses, but we do not recommend it. If possible, fit one between the cylinder and crankcase and one in the cylinder head.
The shims listed here are only applicable between the crankcase and the cylinder. If available, cylinder head shims are listed in the related parts tab.
The correct way to calculate the compression ratio can be found at this link: https://www.paruzzi.com/uk/tech/engine-calculator.php
Next to the thickness of each shim, the inside diameter is listed, along with the common cylinder bores it corresponds to . Measure the underside of your cylinder to ensure you are ordering the correct size.
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