engine misses yamaha waverunner 3 650 need help

[capriceondros]

just installed new 650 from sbt motor will idle but only for a minute back fires occationally when turning over . have checked the whole ignition system trigger and exciter are well into spec. ignition coil has correct continuity has spark both cyl. both cyl 155 psi. opened the new carb and checked the jets low 120 high 115 correct and set mixture screw to factory, right now have no fuel filter just to eliminate the possibility. brand new sparkplugs, new starter new battery


can anyone help me?