No experience on the X300, but experience on the 07 650 Versys and the 2015 650 Versys. Tight exhaust on the 07 at 25,000 KM and on the 2015 at 11,000, just did my second valve shim, post is elsewhere on the forum ./ Short story, the work I did at 11,000 KM which had tight intake and exhaust ,remains the same as I set it in 2017, so turn around was much faster at 35,000 KM March 2021.
The largest time spent is removing and installing the plastic and valve cover , air box, throttle bodies, clutch cable and throttle cable. Yes after fighting with the 2015 once, and ending up removing everything as described, this time I just did it. To get a valve shim done where adjustments are needed, if you get it under $600 USA you are doing good, if they took the time to give before and after measurements, do everyone a favour and give the name and location, as they are a rare find.
here is my march post;
:welcome: Don't fear the valves! :grin2: Here's a video that will give you a good idea. Get the service manual (either hard copy or download) and you should be good to go. Here's another video to give you a better idea what the valves and shims look like:
www.kawasakiversys.com