It sounds like a big push rod boxer engine with solid lifters.
Solid lifters need adjustment and are noisier than hydraulic lifters.Hydraulic lifters use oil pressure to keep the tolerance adjusted to valve clearance.Solid are just that.Soild,no leeway.The solid adjuster keeps the valve train in a fixed setting so as the engine gets hotter the lifter should quiet down if properly adjusted.The hydraulic lifter self adjusts with oil pressure so less noisy and no adjustment.
Not sure how many miles you have on your bike but when you change the break in oil at 600 the 15w50 should help.The lifters need checked and adjusted at 6,000 or 10,000K.
Last thing,the bike is always goona sound noisier in the garage and take awhile to warm up.I let my bkie run for 5 minutes in the garage the other day and the oil cooler was still cold to touch.
To me,It doesn't sound any noisier than my bike.Hope that helps .