I have used Seafoam in all kinds of motors for years and continue to do so. However...... I was in a marine repair shop this past summer and the mechanic brought out a piston from a small engine. Seems the owner liked the product so much he used lots..... and lots in a single tank to clean it up. Burned a nasty hole right through the pistion. Mechanic said he see's it fairly often. Morale of the story, Use in recommended doses. Too much of a good thing is not a good thing!
As I have seen and read used in the proper concentrations it will clean old tar and Gas buildup out of your carberation and engine. But as stated by Calrippem don't go overboard put it in, fill the tank up to the top and drive it untill the gas is almost gone. Then refill the tank with just gas and drive some more. You can then try it again if it still seems to need help. But don't use it as an additive for every tank it's not designed for that and could become a problem rather than a help. Forget what Heinlein said "Everything in excess moderation is for monks" Have fun and keep the rubber side down....
Also, don't forget that other bits of the system are "cleaned" as well... If you've not replaced your fuel filter regularly, you'll be cleaning that and passing the effluent through your injectors...
Tha said, I run Seafoam through EFI systems all the time (as a PM after a fuel lfilter change and "as needed") -- I particularly like how Seafoam stabilizes fuel since a few of the tanks/engines can sit for months.
I use SEAFOAM in every gas engine I have. I do however change fuel filters on a regular basis.
I use this instead of STABIL or other additives for storage. Being that SEAFOAM also cleans your systems my advise is to change your fuel filter at the beginning of the season, after the SEAFOAM has had the chance to dissolved all the grud that might be in your tank and fuel line. Roll your bike out, Change the Fuel Filter, THEN and ONLY THEN start it for the first time.
On my '97 I try to run it at least once a month. On my other machines, Mower, Tractor, Snow Blower etc, I store them with SEAFOAM, and have not had a problem stating any of them since.
i agree with kcid... if you have a fuel tank situation that you know rust is involved... do NOT allow seafoam to sit in your tank for any extended period. if you do.. Then you will need a new fuel filter.. possibly several fuel filters depending on the condition of the fuel tank... in clean tanks.. seafoam is great.. in older tanks showing evidence of rust. it's not a good idea to leave seafoam in contact with the tank walls for ant extended length of time.. since it will pull corrosion off the tank walls. allowing it to settle into the bottom of the tank... and at the first starting after long storage.. This will be the very first thing sucked into your filter. or, fuel system.... and you will be purchasing a multitude of fuel filters. ! The best thing to do is remove the fuel tank entirely.. and do a complete cleaning if you know your tank has interior rust issues. BEFORE you add seafoam. or use it as a stabilizer.. I would suggest you use "Marvel Mystery Oil"... in your tank.. As this leaves a light oil film behind... Not to mention it's ability to keep carb parts working as they should. Seafoam is great as a occasional fuel system cleaner.. It is never intended for more than that.
I agree with the Marvel Mystery Oil. The product has been around since 1923 and still here doing the same good things... I use a couple ounces every fill up unless I think the bike will sit more than a couple weeks without riding. If so I use Startron in the fuel.