Upon starting, left float bowl leaks fuel onto floor. What is float level; I do not have a gauge.

if the carburetor keeps flooding out, the float could be stuck in the up position. tap lightly on & around fuel reservoir to free. depending on age of carburetor, you might need to put in a carburetor kit.

if you got a carb then its the overflow pipe from the fuel bowl and the float is stuck or wrong height setting , or fuel feed pipe perished or tank ! try starting then turn fuel off and see if leak stops !

The float needle has jelled fuel holding it open, rust from your tank is holding the float needle open, The float needle tip is damaged, or you have a sunk float. Take apart clean and inspect your carburetor. Replace any worn or damaged parts.

The float level is too high or the float valve is being hung open by dirt or fuel varnish. First, turn the petcock to the 'off' position and then drain the gasoline from each float bowl by loosening the drain screw on the bottom. Close the drain screws and turn the petcock back on. Check to see if the problem is still there.
If so, then the float bowls will have to be removed and the float valves cleaned and inspected for wear. Also, take each float and shake it while listening for any fuel that may have leaked inside. Any float that has gasoline in it must be replaced. Upon reinstalling the float valves, check to see that the arms on the float are parallel to the float bowl gasket surface just as the float contacts the float valve. This is the correct float level. Adjust the bendable little metal tang on the float to achieve the correct float level.