Hi, my mate at work has a 1978 gsx1000 (or maybe gs1000) but has not been able to ride it for about 6 month now as it is only firing on cylinder 2&3. He said he has changed all the ignition system like coils sparkplugs ht leads ect. and completly rebuilt and cleaned the carbs but cant find the problem. If anyone has any ideas what it could be it would be much appreciated.