apg1991

Hi, I've got a 2005 Dt125 Re and it looses its spark randomly we've tried everything including coil, ecu, Stator, bypassing the ignition, checking wiring with multi meter amongst other things that I can't remember off the top of my head. Anyway when it does finally spark it will rev in the high rev range but as soon as I come off the throttle it dies. has anyone and ideas ? The starter motor is missing if thats anything to go by cheers