The nice thing about the VM36 carb is that you can change the main jet without removing the carb.  Just drain the float bowl and you can access the main jet through the bottom access cover in the bottom of the float bowl.  If I remember correctly, the main jet has a 6mm hex head.  A 1/4" ratchet with a short extension works good.  You might have to put your finger in the air intake side of the carb and hold the jet needle down while you unscrew the main jet (or more likely, when installing the new main jet).  Also, put a shop towel below the carb in case you happen to drop the jet.  (I know from experience....it can and will fall down into never-never land somewhere if you don't.)  

Sounds good.  I need to get some test miles and fuel economy measures using the 200 main before I experiment with going down to a 190 and trying it.  I don't run WOT that often - just don't want to be too lean and hot.