Idle issues and high Rev condition 82 - XJ750

I did total carb rebuild on XJ750 - stock intake with new filter and funky 4-1 pipe. All stock jetting (120MJ, 40PJ y13 needles). Bought new PJ's because someone before me had tried to drill one out but was way too big..... anyway.

I did bench sync, clunk test, and checked all passages for flow. Set idles screws at 2 1/2 turns. Start up was fine, nice throttle response. Once off the choke I had to crank up the idle speed screw a lot to keep it running. Took it for a drive and ran great ...except idle kept on hanging. Did a spray test to see if i had any vacuum leaks - ok.

I went back to shop and re-routed cable and rechecked mixture screws etc. Even on lift it will start up fine like before , then it will go into that hanging idle even with tank off. I'm thinking i need to get it to idle better with mixture screw adjust and get idle speed screw down so it is not trying to run on pilot jet holes. Any other suggestions?

 

Sounds like it's running extremely lean on the idle circuit. Maybe try 3 turns out and see how it reacts?

I was sync'in my carbs this weekend and after getting it all put back together it was running like yours. Turns out that i forgot to put the rubber cap on the right sync port so it was running WAY lean on that side.

Something to check.

 

bench sync is only to get it close, do a sync with it running using what ever tools, method you choose
you'll be a happy camper

 

it wasn't a bench sync that i did i meant flip the gas back on the bike etc when i say "put her back together"

 

i found the carb boot caps were going soft when hot & then sucking air.
just a thought.

 

Ok , I need next size up PJ from 40 to 41.

I had to turn idle screws up 5 turns to get it to idle nice. Runs great now.

I was able to turn screw out and get idle to rise on each cylinder and then as I did that I would reduce the idle speed screw.