Mechanical Strange sound from the gear box

[Big Ben]

When I start riding my 02 Road King makes a strange whining - whistleing sound when ever I use the engine to reduce speed. The noise stops after about 5 minutes. Does anyone have any ideas what is is and how to fix it?

[Urrell]

It sounds like it could be the primary chain. On my Sportster it sounded like a jet engine on deceleration when it was too tight.

[banquo]

I had exactly the same on my Softail. Phil suggested the rear belt was too tight, and he was right.
I'd had the back wheel off and miscounted hte turns on the adjusters when I put it back on. You could try that first, especially if it's recently been adjusted...