So i just got done rejetting my 98 cbr919rr,and hooked it all back up and was about to use the motion pro carb synchronizer,I had the fuel line hooked up to a fuel funnel and had the motion pro set up,started the bike and let her run,she started to run pretty high into 3500-4000 rpms and the settled down to 1300 rpms,and she sounded all right just a little out of sync but before i could start the sync process she started to backfire from the #3 carb,I shut her down and let her settle while i tried to figure out why,couldnt figure anything out so i restarted her and she did the same thing,high rpm then right back to low 1000s rpms,then she backfired once again from the #3 carb,i could really use some advice on this one,kinda stumped on why shes doing it since she does it periodically while idling instead of continuously backfiring.

 

I would take that no 3 carb apart again and make sure everything is legit inside. That would be a good start at least.

 

alright i'll try that,i'm about to go and make sure the boots are properly secured down and then i'm going to try to spray some carb spray on the boot areas,and make sure the hoses are nice and tight and theres no leaks,read in a different forum that backfire from exhaust its to rich and backfire from the carbs its to lean,another site said blipping the throttle will do it,another said that a vacuum leak will do it,so im goint to knock out the vacuum leak then i'm going to adjust the pilot jet on that 3rd carb,if none of these work i'll take your advice and take the carbs back off and tear them apart,and give them another thorough cleaning

 

synced her when she was running fine after i let her warm up but now shes acting up again

heres a video of her acting up

 

jetting could be set wrong. bikes in general dont run well without the airbox, too much air and it runs lean. put the air box with filter and see how it runs. have the airbox is like having a vacuum leak.