My wife had an old ZZR400 (basically a sleeved down 600) we picked up cheap off a friend... and it was shit. Big, heavy and gutless. Though we never did get it running quite right - kept cutting out in top gear over 10k rpm. Forever messing about getting a good seal on ram air box, had misfires from old HT leads, fuel tap kept leaking, tried bypassing Jap limiter and the rest. Probably just had a bad example that had been bodged by many before, but put me right off!
Hope yours turns out better though as they aren't supposed to be that bad!