Got motor running,new plugs,wires and a fresh set of carbs. The jet worked it self out of carb. on rear cyl.and was flooding it out. Fixed that problem , now it wants to pop and back fire. I can start it up pull plug wire off of rear and can tell it is not firing like it should,new plugs and switched coils around same thing.any idea's? I'm at my wits end. Just did a comp. test it is low on rear cyl 90 psi cold rear and 140 psi front would that do it?   Thank you in advance for any and all help Jeremy

You don't say if the bike has been sitting arond for any length
of time but the fact you have swapped coils seems to suggest
something mechanical. stuck rings or corroded valve seats but dont
forget to check the ignition pickups if you have any other ideas
or questions email me address in drivers section
  Roy