Idle adjustment doesn't work

Hello. I would like to ask the well minded and experienced people here how is the idle screw fitted to the carbs. I will describe what is happening. My carbs are fully rebuild by a professional person and I've spent a shit lots of money on that. Carbs fitted but not balanced. Anyway I had a problems with spark that is solved now so I turn the key pull choke bike fires up first time (engine cold) When warms up it dies due to too much air going in so I pull the choke off and revs goes up to 5k. I'm trying to adjust the idle screw to bring the revs down but without effect. I've checked the throttle cable and it's loose so I think the idle screw is to blame. My question is: can this be fixed without taking carbs off the bike? haynes manual doesn't say anything about it.

 

you are talking about the knob adjuster between the carbs at the rear of them?
it sounds as if you have an air leak possibly at the manifold boots all your clamps tight? propane test or use carb cleaner to check for leaks.
you should have bench synced the carbs before installing them . was this done?
your idle adjuster adjusts carb 3 to which all others are synced
you could try to sync the carbs it is discribed in the diy forums

 

Yes. That's knob behind the carbs I'm talking about. Air leak from manifold rubbers? I bought them second hand and all looks good. I'll check them again. But that little knob doesn't react whichever way I turn it. I have to say that this workshop that overhaul the carbs they bench synced them.

 

Which bike?

 

Xj650 UK model 4kO 11N

 

maybe talk to him because of that statement.
but in his defence he needs the bike to do the running sync.
to do it yourself, you'll need a sync tool of your choice. commercial or homemade, they all get the job done.
now you're going to hear about setting the valves first or the sync is useless, setting the valves won't bring that idle down

 

I had this problem on my Virago, but that was because someone had installed the throttle cam 180 degrees off - putting the tab that the idle screw presses on nowhere near the idle screw. Not sure if that's possible on the XJ rack.

 

I'll take the carbs off the bike and check everything again. Thanks

 

before you do that , if the idle screw doesn't make any difference when backed all the way out , try pushing down on the throttle shaft linkage , maybe the shafts are sticking slightly , holding open the butterflies.
stu

 

It is failry possible that the little arm the throttle cable attaches to is not moving down freely. Remove the tank and have a look down there between carb #2 and #3.

 

Did the carb guy replace the throttle shaft seals?

 

when you turn the knob in can you feel or see any movement on the adjustment screw on carb 3

check this statment out

and this one

 

could be that the bench sync has the butterflies open to far resulting in high idle. try backing off the #3 adjuster screw(between carb 2 & 3) 1/4 to 1/2 turn and see if the rpm drops
or if you have the carbs off re bench sync them
it is the knob that sets carb 3 for the bench sync

 

I think it's possible to reassemble the carb bank in such a way that the throttle linkage is blocked from dropping to the idle position. I think I've done this in the past. It isn't apparent until you start the bike. From (vague) memory it isn't difficult to fix. This seems to agree with what SQLGuy and others have said.

 

heres a link full of pics for hatachi carbs some photos of the possible problem area
http://www.xjbikes.com/forums/threads/first-time-taking-apart-carburetors-lots-of-pics.48063/

 

Sometimes the human factor plays a role in things we do (I've done it plenty times). If you remove the carbs to re-visit the bench synch make certain the orientation of the washer, spring and o-ring is correct for each mix screw. Then from soft bottom set them 2.75 turns out. Hope this helps.

Gary H.

 

This happened to me after j rebuilt my carbs a week or so ago. Put them on the bike hit the choke and started her up. Ran good for a sec then died on me. Cranked her back up with no choke and she damn near redlined. I shut it off and turned it back on same thing. This went on for about a half hour of me messing with the idle screw and everything. I was stumped...


Then I took the carbs off, put them back on, ran fine and has since.

Either I had a problem with the intake boots not being sealed all the way or something had the throttle stuck open. Either way, take your carbs off readjust the clamps and put it back on. Could be just that simple.

 

Thanks for that. I'll definitely try that that.

 

Ofcourse. I've received so much great info on these boards thru the last couple weeks of lurking. With that said, like any other hobbyist board, some people often over complicate things. Before you start ripping the carbs open again just be sure the carbs are ALL THE WAY IN on the intake boots and the throttle lever on the carb itself is not hung up on anything.

 

Hello. Update on situation folks. I've lifted the fuel tank and noticed that the idle screw doesn't reach the leaver that should push or release. Because it's too far, I've spoke to the guy that rebuild them and dropping it off tomorrow so he will fix what he messed up.

 

Looks like the bolt is bent causing it to bind through the grommet. Are the threads stripped?

Gary H.

 

makes you wonder how he bench synced the carbs.
he could have used the light method and done them all to #3.
before you reinstall them check the bench sync come and ask how thats done

 

Will do so.

 

It makes me think one of the three linkages between carbs wasn't reassemblied properly.

 

Hello again. I've checked the carbs and put them back in and bike work but a bit rough and too rich as the carbs has not been balanced yet. Revs are fine but bike struggle over 5k rev on open throttle but when open the gas gently it goes up and when reach 7k revs it goes like hell. At the moment I am working on crank case gasket replacement and oil seal, oil change and filter, checking oil sensor too.