Having a goobered carb it doesn't follow that the cases should be split to clean stuff.
Last I looked a well known internationally known bike shop charged $150 to split a kdx case. That is with the engine sitting in their shop...out of the bike!
Unless you suspect or know a problem exists....or maybe are just looking for something to spend your money on it isn't reasonable to take the thing apart.
If you do, it likewise doesn't make sense to put it back together without new bearings and seals. That would include crank bearings/seals, bottom rod, transmission shaft bearings and seals where used. Drums and shift forks are fairly high wear items in bike engines.
You don't split the thing without a tool of some sort. Some folks have made their own or you can buy one from an outfit like MotionPro. Generally they can be put back together using the bolts to squeeze the pieces back together.
This is a big job. It's not unheard of to put an engine back together only to have the crank not turn, be unbalanced or incorrectly indexed.
Doesn't mean it isn't possible......