KX 250 1999 Crankcase question?

I've been doing a rebuild on my kx 250. The problem i'm running into is when putting the lower case halves together. I'm using RTV sealant w/o a gasket. After the RTV is set and I begin to press the crank/bearing into the left side case everything is fine. When i go to tighten the crankcase bolts the transmission seizes...when the bolts are loose it rotates freely but the second I put any pressure on the crankcase bolts the transmission gears seize. Could the lack of a gasket cause this or is it possible im missing a spacer or have one on backwards. It goes from turning with 2 fingers to seized in about 1/16-1/8". My process of using the RTV is put a thin layer on both halves of the crankcases...let sit for 10 min...and then tighten until it begins to come out from between the halves...no gap between the halves. HELP!!!! I'VE TAKEN THIS THING APART 3X SO FAR...GETTING VERY FRUSTRATING!!!