Re: 20 seconds runnin time.
Check the connections from the engine to the cdi. Pretty crappy connectors. I cut mine off and soldered the wires together, check where the spark plug wire screws into CDI and into plug cap, iside cap is also screw that might be loose, mine was. Best bet get a new plug, plug wire and cap at auto parts store. Also if you hooked up your kill switch disconnect it till you firgure eveything out