FYI, There´s only one carb on this bike, feeding both cylinders. Fuel additives such as Sea Foam should work fine. Here´s a little story that may do a little more than answer your question: I blew through several Sea Foam/Gas tanks in my cm250c and it helped a little bit, but the bike still sputters and hesitates a little, more when it´s cold. So then I tried putting an even higher concentration of Sea Foam into the tank by pouring it in when empty and running the bike for a few minutes to draw the mixture into the carb. The first time I did this, when it finally started, a huge black cloud came out of my mufflers! That seemed like a good thing to me. But it was still running poorly when cold. Convinced it´s the carb, and too stubborn to just take the carb apart and clean it, I tried once again to run high concentration Sea Foam into the carb via the tank. This time I put an entire bottle into an almost empty tank and ran it for several minutes. Then I turned off the engine and left it sitting for about a week. I haven´t been able to get the bike started since! So now I´m trying to figure out how to flush the sea foam and its crud out the carb.