![Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021 Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021](https://cross-mania.com/23992-large_default/kit-athena-big-bore-o72mm-300cc-for-yamaha-yz-250-from-2003-to-2021.jpg)
![Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021 Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021](https://cross-mania.com/23992-side_product_default/kit-athena-big-bore-o72mm-300cc-for-yamaha-yz-250-from-2003-to-2021.jpg)
![Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021 Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021](https://cross-mania.com/23993-side_product_default/kit-athena-big-bore-o72mm-300cc-for-yamaha-yz-250-from-2003-to-2021.jpg)
![Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021 Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021](https://cross-mania.com/23989-side_product_default/kit-athena-big-bore-o72mm-300cc-for-yamaha-yz-250-from-2003-to-2021.jpg)
![Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021 Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021](https://cross-mania.com/23991-side_product_default/kit-athena-big-bore-o72mm-300cc-for-yamaha-yz-250-from-2003-to-2021.jpg)
![Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021 Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021](https://cross-mania.com/23990-side_product_default/kit-athena-big-bore-o72mm-300cc-for-yamaha-yz-250-from-2003-to-2021.jpg)
![Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021 Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021](https://cross-mania.com/23987-side_product_default/kit-athena-big-bore-o72mm-300cc-for-yamaha-yz-250-from-2003-to-2021.jpg)
![Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021 Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021](https://cross-mania.com/23988-side_product_default/kit-athena-big-bore-o72mm-300cc-for-yamaha-yz-250-from-2003-to-2021.jpg)
![Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021 Kit ATHENA BIG BORE Ø72mm 300cc for YAMAHA YZ 250 from 2003 to 2021](https://cross-mania.com/21922-side_product_default/kit-athena-big-bore-o72mm-300cc-for-yamaha-yz-250-from-2003-to-2021.jpg)
Here is the big bore kit proposed by ATHENA to increase the capacity of your motocross / enduro YAMAHA YZ 250cc from 2003 to 2021. This kit in Ø72mm against Ø66mm of origin thus makes it possible to pass your motor bike of 250cc has 294cc real! A gain of torque and performance will be immediately felt. It allows a gain of 4 HP on average which is huge on this vehicle. You go from 41hp to 45.3hp thanks to the high engine ATHENA BIG BORE. Enough to have fun on the tracks or in the forest. ATHENA has also planned things well because this top engine is sold complete. It includes the cylinder, piston, ring, cylinder head and all the gaskets you need for a quality and tight reassembly. The advantage of taking this engine is that it is designed to be mounted on the original connecting rod, so you have no modification to do! Attached is the power curve so that you can see for yourself the difference between the original and the big bore. We have also provided you with the assembly instructions if you wish to have more information on the assembly of this kit for example the adjustment of the squish. You will also find a detailed list of vehicles on which this cylinder can be mounted.
Fits on:
YAMAHA YZ 250 (CG13) 250 2003
YAMAHA YZ 250 (CG17) 250 2004
YAMAHA YZ 250 (CG20) 250 2005
YAMAHA YZ 250 (CG23) 250 2021
YAMAHA YZ 250 (CG23) 250 2020
YAMAHA YZ 250 (CG23) 250 2019
YAMAHA YZ 250 (CG23) 250 2018
YAMAHA YZ 250 (CG23) 250 2017
YAMAHA YZ 250 (CG23) 250 2016
YAMAHA YZ 250 (CG23) 250 2015
YAMAHA YZ 250 (CG23) 250 2014
YAMAHA YZ 250 (CG23) 250 2013
YAMAHA YZ 250 (CG23) 250 2012
YAMAHA YZ 250 (CG23) 250 2011
YAMAHA YZ 250 (CG23) 250 2010
YAMAHA YZ 250 (CG23) 250 2009
YAMAHA YZ 250 (CG23) 250 2008
YAMAHA YZ 250 (CG23) 250 2007
YAMAHA YZ 250 (CG23) 250 2006
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