Bought wrecked bike. Main harness was scrapped. Removed plug connection and spliced wires together. I put in New battery (load tested). Used Starter (ebay). Stator good & r/r. No problem with charging system. Runs great. Only starts if it has been sitting on trickle charger. Only starts on charger @ 13 plus volts. Voltage drops a lot at start up but runs normal. Noticed tachometer goes up when turning on but stays at zero rpm. What do I check next?