I have a xvs 650 and I’m looking at doing a complete rebuild, wandering if I couldn’t stroke it and do some high compression pistons with a better cam??
Been wondering the same for nearly 20yrs!!!
It seems that there are absolutely NO modified engine parts for this base.
HOWEVER, the SUPPORTING systems, that were specifically designed and engineered with purpose, CAN be modified and/or replaced with supporting systems for improved 'street' performance.
Most notable of course, are the limited exhaust and air intake systems.
But there are also MUCH improved carburetor/manifold systems and far better ignition systems that allow for greater flexibility, improved performance bands, and greater power output of the base engine. Especially if simple engine base mods are effected.
As an example, a modified valve spring seat could easily be machined for slight increase in valve spring force. With a custom programable ignition module, the 7200rpm limit could be modestly increased (within reason) for greater gear range and top speed without valve float concerns.