Just drive it gently. It will go away. Eventually. This is common.

Don't waste your money. They will adjust them, they will put special oils
in the engine, but nothing fixes it like some driving.

>I let my 87 Westy sit unused for a couple of months.  When I started it up I
>heard some loud valve (I assume) ticking that I expected to go away after a
>few seconds, but did not.  Later I let it idle for awhile to get up to
>"operating temperature" and it still didn't go away.

Chris Mills in TN