So i bought my 2009 drz400sm with 30,000km used off this sketchy guy. He said that when u ride the bike in 5th gear it will make a odd grinding/ buzzing noise. "all you need is a new chain and the sound will go away"..... Anyways i took his word for it and realized ive been tricked.So my problem here is that when i kick the bike into 5th gear and release the clutch and give a bit of throttle it starts to make this awefull grinding/buzzing/ metal scraping sound. My speed when i kick it into 5th gear is around 80-85kph or around 50mph. its pretty loud and definitely noticeable. the sound goes away when i dont give it any throttle. from gears 1-4 i have no problems and bike runs great. ive tried to go faster (100kph+) and then switch into 5th, same problem. how i realized this sound was coming from the engine and not because of the chain was because i took off the chain and ran the engine in 5th gear and the noise was there. so anyways in the mean time i installed my new chain and new engine sprocket and rear sprocket and im ridding with that now. i have also changed the oil also. gears 1-4----no problem 5th gear---clutch engaged--no throttle--no noise 5th gear---clutch engaged-- +throttle--Noise grinding. please help, im out of ideas!!