Motorcycle Repair: 83 Honda 650 Nighthawk, honda 650 nighthawk, cold start

Question
Hi David, my bike only runs on the two center cylinders until it runs for about 20 minutes and gets hot. I have checked the compression on all cyls. while cold, they all read 140lbs. I even swapped coils from side to side and it still only runs on the #2 and #3 cyls. until hot, any help would be appreciated.  Thanks alot, Terry

Answer
Hello Terry,

you have swapped the  two coils that for sure are fireing with the two that are not? I have never seen are heard of a cold start on this bike. All else i know it could be is the CDI box. do you know anyone with the same kind of bike to uee a part? I would have to lean towards the CDI if the fireing is not happing on the wire's leading to them coil's.. And after  20 minutes i dont know about.. the CDI box only works for like 1 min, to get spark to them coils after that the motor pulls the rest.. good luck but im leaning towards the CDI box i hope this was help