I have the same problem with my 86 FZ750. After recently doing a complete engine disassembly to replace a bent shift fork, i had access to the problem area. The culprit is the starter clutch assembly that drives the chain on the crankshaft. Without repairing it, the best way to get the bike restarted when that horrible sound occurs from the starter clutch skipping over the gears is to simply get a rolling start and pop it into 1st gear while simultaneously hitting the starter button. Mine fires right up every time. Good luck!