I rebuilt mine with no gasket between the two crankcase halves, only used a thin film of Yamaha non-setting gasket that I use on the SRX's. Honda sealant is equally as good and shimmed accordingly.
I cleaned everything up then nipped the mounting bolts up. 650km since rebuild. Added another 25km and it hasn't reappeared.
That is what is making me feel queasy. You appear to have squeezed the crankcases together and closed a gap between their mating surfaces by tightening the engine mounting bolts and not by tightening the cap screws holding the cases together! Case faces may not be true, either due to warping or butchery?
The 6mm cap screws are only torqued to 7ft/lbs (9.45Nm).
Good health, Bill