So I was pulling a small trailer. It had just stopped pouring rain. And I put in 4x4 and locked position bc I was going up a hill. It started smoking in the center of the bike. I stopped immediately. So it still pulls without slipping. But has a bad rattling noise. I do all my own repairs on my truck and tractors. But I know very little on bikes. What do I need to do first. Thanks

[2015 Z Force 800 53/Trail EPS]

Have to determine what it is. So does it do this in and out of 4wd or just in 4wd. Is it from the engine or something else. Are all the engine mounts intact and is there any signs of oil leakage. My guess is from your description she has lost the engine for some reason.