it could be a couple of diffrent things actually, 1, the float is set to high causing gas to run out of the float bowl overflow tube, " unlikely if the bike wasent doing it before and you didnt touch the carb, 2, the float needle may be defective by this mean it may not be seated corectly," possiable but also unlikely" 3 you may have had some small particles of dirt when you poured your gas in, "very likely" do yourself a favor and buy a funnel with a filter in it, team kaw factory riders filter their gas 3 times to be sure not to get any dirt in their tanks, to fix it just pull the carb off, then pull the float bowl and clean the float needle also look at it to see if it is marred in any way if it is it will need to be replaced be careful not to bend the tangs on the float itself that set the float level, good luck.
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