Jamespellegrino

Hello, I have a Yamaha Maxim 700 from 1986. I'm getting a high pitched noise, like the revving of a windup toy, when I am between 10 and 25 mph. It doesn't happen when idling or going slow, but it'll happen in any gear between 10 and 25 mph. I think it is coming from the engine, but I'm not sure. Any idea what this might be? James