So did you use a dry paper gasket this time?
I was taught way back to oil a paper gasket when you install it. I was told this starts the swelling process. It's the swelling that does the sealing.
I was also told to not get excited if it leaked at first. Wait a day or 2 than tighten again. It was explained to do this 3 times, than change the gasket if it still leaks.
I dont like the idea of yamabond (three bond I believe is the identical product) on any cover that's already hard to get off.
Take the outer timing cover for instance. Once that yamabond is sealed for a while, it's going to be hard to get that cover off without trying to jam something into the joint to force the covers apart. There is nothing to grab to pull the cover off, rubber hammer won't shift that stuff, your backing yourself into a corner.
If I am using yamabond, it's on one side of the gasket, grease on the other. I am putting yamabond on the part that comes off and I can get away from the bike. That way when I have to go back in there in the future I can scrap off the gasket and sealant without getting crap inside the motor.
I also like gaskacinch, it's like a rubber cement. One or both sides, but again it will glue covers down pretty well.
Try to never use silicone on anything. It's for leaking roof gutters and plugging oil passages.
Lee