What's the history on this bike? Has it been abused (red-lined during break-in period, etc.)? I'm wondering about bent shift fork, valve train, or cam chain issues. If the whine is constant with the throttle ONLY in 4th, 5th, and 6th, it might be in the shifting forks.
Is the noise coming from inside or outside the engine? All the sprocket/chain stuff aligned and no wear pattern (cocked, etc.)? Any leaks around the head or tranny?

 

 

as far as history goes,I got bike with 2000 miles on it in 05, I took care of it. It now has 12,500 miles on it. Cant tell where noise is comming from. Today I will ride with out helmet and pin point noise. It started when i think after I changed rear sprocket and chain. My front sprocket has broke tooth. I do have new just waiting for buddy to bring impact over. Also I do believe that I heard the noise in third as well before I shift into 4th.

 

Make sure to Hold The Back Brack Down When Removing The Nut From The Front Sprocket

 

Rule #1: Don't ride without your helmet. Your head is worth more than the bike.

Get rid of that front sprocket. It's an accident waiting to happen, and probably what is causing your noise. Is your chain too tight?

Stay safe!

 

yes indeed.