Any time I pick up a previous owned bike I pour in some Berrymans injector cleaner in the tank , I like it better than S foam. better price also. In some cases I have taken the injectors off and soaked them in Berrymans make sure you take the O rings off or they will swell up. After a few days the will shrink back to size. On one 08 XBS I poured Berrymans in the fuel line disconnect line on top for a straight shot in the injectors.
https://www.walmart.com/ip/B-12-Chem...&wl13=&veh=sem