On my YZ490J just behind the magnesium crankcase cover where the kickstarter is it looks like its welded but there is also a black puddy type of stuff on it.
This bike has a jetting problem and the case has to be removed to make sure tranny oil is not gettin through a bad seal and into the motor through the crankcase causing a rich mixture, before i can attempt to jet the bike.
I'm afraid i may run into problems since there is like a black puddy around the top of the kickstarter casing and welding on the back of it, maybe JB weld, can the case still be removed?
The magneto side of the crankcase is fine, no welding or cracks.
the bottom of the engine needs to be took apart so i can find out what needs repairs such as crank seals or bearings, i beleave the topend of the engine is fine