Leaking Carb overflow 01 520 EXC

Of late the old carb is leaking fuel 70% of the time from a small tube on the bottom of it. Its dripping out at a rate of about 1 drip every 2 seconds or so.

Is this a float issue?

I havent pulled the carb out of the bike before as its been serviced by the shop but would prefer to fix this myself if possible.

Any ideas?


If it is the hose coming out of the bottom of the carb on the port side, then almost definitly a stuck float issue or ,float hight issue ,clean the bike(very important)take the seat and tank off lossen the flat head screws( port side)then twist the carb bottom to port and the top to starbord take the allen screws out of the four corners pull of the bottom of the carb (care full float retaner pin is loose)take the float off and clean the float valve(aluminum piece shaped like a pencil point)reassemble and you should be good to go dont leave carb cleaner in the carb to long it will soften all the rubber parts --good luck

Excellent job Matt, thanks for the informative advice... seems within my technical abilities


Matt covered the needle & seat nicly, the next problem spot is an Oring seal where the seat fits into the carb body. to test remove the float and seperate the needle, wipe hand and parts dry, put the needle back in and hold it with one finger, slide a clean paper towel under it then turn the fuel supply keeping the neddle firmly held in so we know gas is not coming thru the needle & seat, then is it drips it is likly coming around the seat indication the Oring above has failed.

Thanks Dave, I will look at that as well... might just replace the seal while Im at it if I can the part easy enough.


I have a 2002 EXC 520. Gas poors out of the carb overflow tube when the bike is off - doesn't seem to leak much when the bike is running. The float seems fine. Has anyone solved this issue by replacing the rubber needle and seat?


I have a 2002 EXC 520. Gas poors out of the carb overflow tube when the bike is off - doesn't seem to leak much when the bike is running. The float seems fine. Has anyone solved this issue by replacing the rubber needle and seat?


just read the even posts above for the answer:excuseme:

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