Fuel leaking from the overflow is a common problem. Try a search on the home page of our forum with the words "overflow tube" and see what you find.
As far as fixing it, most of the time it's caused by a sticky float pin, or a bad seal between the needle valve and its seat. Checking that needle valve usually involves removing the carb bank. Look for a little cut line in the neoprene end of the valve. Also, you can lap the seat portion with some cotton on a swab and a bit of cleaner. I've read where some will run a VERY mild abrasive on the seat to get it clean, but you do this at your own risk.
You can tap the carb lightly with a rubber or nylon mallet to see if it will stop. I would not recommend using a steel hammer near there, as sparks and gas fumes can be a volatile mix.
Sea-Foam is a wonderful thing, but I don't think it will help you much if you have something mechanically wrong with this carb. It can clean, and maintain a level of clean, but it won't unstick a needle valve or float.
If you wish to remove the carb bowl on #2, you'll have some trouble getting the bowl screws out. Again, it may be easier to remove the whole bank and check it that way.
There is no need to re-sync the carbs if you're just checking the bowls. You'll need to re-sync if you've changed the throttle screws/nut settings on the throttle mechanism. It won't hurt to check them once a year or so. Some guys do it once a month, but I find that a bit more AR than necessary. Carbs may tend to drift a bit over time, but the change may be so slight as one wouldn't notice. Check it once a year.
I hope this helps. If you're new, welcome, and keep us in the loop.
Luke M
Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.
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