If you only want one infowindow ever, only create one InfoWindow (in the global scope), reuse it and change its contents when a marker is clicked, close it if the user clicks on the map.
similar question
var iw = new google.maps.InfoWindow(); // single global infowindow
google.maps.event.addListener(map, 'click', function() {
iw.close();
});
function bindInfoWindow(marker, map, title, race, loc, org, web, link) {
google.maps.event.addListener(marker, 'click', function() {
iw.close();
var html= "<div style='color:#000;background-color:#fff;padding:5px;width:250px;'><h4>"+title+"</h4><p>Race</p><h4>"+race+"</h4><p>Location</p><h4>"+loc+"</h4><hr /><p>Organizzazione</p><h4>"+org+"</h4><a href='"+link+"'' >"+web+"<a></div>";
iw.setContent(html);
iw.open(map,marker);
});
}
working fiddle - different code as you didn't provide a complete example, demonstrates the concept.
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