i have a 81 yamaha 650 and it is not getting spark. I replaced the coil with another one ( used ) and is still not getting spark.It used to start ran for about 20 seconds then it died. I got this bike from soem guy and paid only $ 200 for 2 of them, i have another one as a parts bike.I got new plugs checked all the wiring and fuses, ther was a short in the head lamp and took out the head lamp , then it started once or twice and now it dont do nuttin, any help would be helpful ,thanks