Here's why:
* Bore size: The XS650 has a larger bore diameter than the XS400. This means the cylinders are physically too big to fit onto the XS400's smaller crankshaft.
* Stroke: While the XS650 and XS400 share the same stroke length, the bore difference makes the cylinders incompatible.
* Connecting Rods: The XS650 connecting rods are longer to accommodate the larger stroke and bore.
In short, the XS650 and XS400 engines have different internal dimensions, making their cylinders incompatible.
If you're looking to upgrade your XS400, consider these options:
* XS400 Big Bore Kit: These kits increase the bore size of your existing XS400 cylinders, giving you more power.
* XS650 Engine Swap: This is a more complex but rewarding option, giving you the full benefit of the larger XS650 engine.
Remember to do your research and ensure the parts you choose are compatible with your specific model before attempting any modifications.
