1982 honda atc whine when cold

[1982 honda]

i bought a 1982 honda atc 200 a couple months ago as the original owner died and his wife didnt want it Runs and drives great but it has a bit of a whine that gos away when its cold other than that the engine sounds beautiful. i was just wondering if its normal or if its something i should worry about have heard it on other trikes but i want to take care of this one.

[1982 honda]

not sure how to add photo any help would be greatly appreciated