I have 2 1982 yamaha xs 400 rj seca's. Blue one is hard starting. One day you can run it ,the next it doesn't want to run. Or when it is cool in the morning it won't start. I've changed batteries ,starters,plugs......everything that would come off the bike (except the wiring harness )I switched out with the other one... (red one ) Even changed the motor as a last resort. It is still not right. Put the motor from the blue one in the red one and the red one started right up ...even with year old gas in it.What else can I try ,what am I missing.??? Any help would be greatly appreciated !