Internal engine noise

Afraid that sounds like the ends are gone, the best way to tell is to get a compression test done on it, but you can usually work it out for yourself.
The engine is under most strain when the power demand is highest for example when accelerating uphill from a slow rolling speed. you will also get the knocking on the overrun, i.e when you have been running at a higher speed and you shut the throttle. When maintaining the same speed does the knocking get more or less? if its less then its almost certain the ends have gone
If as I think it is the ends (usually the big ends rather than the little ends) I afraid its probably terminal. the cost of repair would be too high.
Be careful when riding as the probable result of worn end shells is a con rod through the side of the block and at speed that could be seriously dangerous

I would tend to believe it's more likely a worn sway bar bushing or link if it's a rattle or a small clunk, if it's a loud clunk probably a strut, try bouncing he back of the car when parked, if you get the clunk probably a strut if only when driving,turning,braking probably just a bushing on the sway bar

you need to be very cautious as this culd very easily be mistaken for a loose rod insert...around 2200 rpm hold the idle steady and see if you here a rattle. Then do it again increase slightly then decrease slightly...if you still here it, its possible an insert has came loose from oil run too low or high mileage wear and tare on the crankshaft..if you love it fix it if you dont trade it quickly...GOD bless

Sorry for the late reply but, no, it is not related to a loose heat shield. It is a louder rattling sound more like a loose bearing vibrating inside either the transmission or the clutch assembly. Only between 1600 and 1900 rpm. and it is not present under ou over these rpm. The rattle desappear when I lock the 4X4. Dealer is out of solution!!

Sounds like time for a new engine to me. (severe engine damage due to oil loss or overheating)

no go over complete bike with wrench and screwdriver--cud also be internal like a bad bearing/loose clutch--gut enuf oil init

sounds like your lifters or valves are rattling!

If this sounds like a tin can rattle it is likely a loose heat shield on top of the catalytic converter. They come loose after time and corrosion take their toll.

had the same issue, had someone look and it seems the noise was caused by heat shield being loose covering exhaust system. Have that checked out.