OEM compression ratio

I have an 08 YZ450f and am going to put a new topend in soon. Was wondering what the stock compression ratio is and if there are any other years that have a higher ratio that will fit. Want to stick with oem.

Thanks

I have an 08 YZ450f and am going to put a new topend in soon. Was wondering what the stock compression ratio is and if there are any other years that have a higher ratio that will fit. Want to stick with oem.

Thanks

The manual says oem bore x stroke = 95.0 x 63.4mm.

Compression ratio = 12.3 : 1

2008 YZ450F(X) Owner's Service Manual page 2-1.

I put a 13.1 PRO X piston in my 07 yz450f, same as stock but higher compression.

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