There is always going to be blow-by. Think of the breathers like the PCV valve (positive crankcase ventilation) on a car. The breather bolts handle all the pressure in the crankcase. With 121 cubic inches there will always be pressure in the crank case from blow-by past the rings plus additional pressure from the oil pump trying to scavenge oil back to the oil tank.
Make sure you are not overfilling the engine oil tank which will only make it worse. If you travel a lot on highway (fast, high rpm’s) it will be more noticeable.
Some people will modify the air cleaner assembly and install an external breather to prevent oil getting burned with the air and fuel mixture. If you think it is excessive check your spark plugs and/or your oil consumption rate. If you're constantly adding a lot of oil between oil changes you might have a problem.