This is a 420/500 to 520(518cc) conversion topend kit with standard size piston, rings, pin, clips, cylinder and gaskets. These are all OE Honda parts in the Honda packaging. This 520 cylinder has been modified to fit all 420 and 2012+ 500 cases without any case cutting. 2007/2008 420's MUST RUN a 2009 or newer head due to water jacket positioning. These are all OE Honda parts in the Honda packaging. We strongly recommend a fuel tuner to correct the air/fuel ratio on the 420 and 500.
**No warranty expressed or implied due to the nature of this product.