Yeah, the base gasket is the worst. Basically you have to tear apart the entire scooter. My GV's motor is much easier to access I see it when I adjust the valv es. Best think is to sell it for parts and get a different brand. I think the Piaggio BV350 is a good choice or burgman 400 etc.
Burgman 400 is not an easy valve adjustment. Shims, etc.
Fortunately has a long service schedule.
Duct tape two or three LIKE200I's together....you'll thank me when valve adjustment time comes......TRUST me on this!
Stig