That's interesting. My CM400T did the same thing, except opposite.
When it was cold (below freezing) the speedo would squeal, and the
colder it was the louder it would squeal. Once it got above about 25
mph it would quiet down. Also, it quieted after driving for about 5-
10 minutes. Sure you don't have the rare T004MC? That model had
similar problems but in reverse.

Dave

--- In honda_nighthawk@yahoogroups.com, Ted Silverman
<miamited33156@...> wrote:
>
> The noise is ocassional, after riding a while. it will stop when I
slow down to 30 MPH. doesn't matter what gear I am in or if hte
clutch is engaged. 
>
> It is kinda a whistling, howling noise that is steady. My other
thought was that it might be brake pads vibrating, or wheel bearings,
but when it happens, it is steady regardless of the speed. and like I
said, once I slow down to 30, weithe rbreaking or coasting, it stops.
>
> Ted
>  A government big enough to give you everything you
> want, is strong enough to take everything you have.
> .........Thomas Jefferson
>
>
>
>
> ________________________________
> From: Dominic Newman <housesoap@...>
> To: honda_nighthawk@yahoogroups.com
> Sent: Monday, January 12, 2009 7:54:59 PM
> Subject: [honda_nighthawk] Re: 84 CB700SC Speedo cable noise
>
>
> i had this problem, maybe, it turned out to be the clocks, the
speedo
> ended up just spinning round.
> i think is was making the cable stick and twist in the housing.
> started happening when i started keeping the in a heated garage.
might
> have helped dried out the oil in the speedo
> dom
>