I cannot adjust the idle screw after i cleaned carburator?

Hello all of you guy i'm Xj Biker from thailand . The problem happen after i
cleaned carb and try to adjust float level by myself.I make sure everything
in specs.But when i start the motor running good so i adjust the mixture screw until the flame is blue .But then i try to low down the engine speed
by adjust idle screw the engine cannot low down the speed.I thought its about 1500 rpm even the idle screw is out!!! but the motor still running ?
My bike is XJ 750 seca. So what wrong about that?

 

Common mistake, Thanh, when you bench sync make sure the idle screw is midway on the thread, so there is plenty of thread to back that sucker off.

 

Thank a lot wizard,Do you mean before adjust the carb first thing i'm gonna
do is adjust the idle screw by midway on the the thread and then go on the prosess(mixture screw,synchonize,etc)

 

One more, slightly related, question. Are you blocking the YICS ports during your mixture adjustment and sync, or is yours an '81?

 

Yes, before you bench sync & set the mixture screws to factory default, they are the last thing to adjust after a running sync.

 

NO k-moe i do not blocking the YICS system port that what i worried about.
Actually i don't know how to blocking YICS system.For all I know they gotto
use a special tool thai i have not.If its nescessary please tell me how to.
Thanx a lot!

 

Re: I cannot adjust the idle screw after i cleaned carburato

There is a special tool required, but there are specs to make it on the forum and member chacal also sells a pretty nice to use as well. I also read that you could use a towel or an old t shirt in the YICS passage. This is accessed by two bolts toward the rear of the engine casing. T shirt isn't the best way of course, but I bet it works better than nothing.

 

Plugging the YICS Passage by packing the Bore with a LONG strip of T-shirt or Pillow Case saturated with Marvel Mystery Oil will do the trick.

The Passage needs to be "Packed-in" from both sides.

A Ram-rod of Fiberglass Driveway Marker makes an effective tool for stuffing the cloth in the Passage.

The IDLE Adjustment Rod should be set to a point where the Number-3 Carb is closed on a Strip of 3 X 5 Card, Business Card or a Narrow Strip of 35mm Film.

Begin with the #-3 Card closed-down on the "Feeler Strip".
Then, match 4 to 3 before setting 1 and 2 to the same drag as 3.

Preset the Idle Mixture Screws out to BETWEEN 2¾ and 3 turns out.
Colortune BLUE is perfect for IDLE.
The Plant needs a bit more than BLUE.

Set the Mixture to BLUE, ... then ADD some Additional Richness by turning the Mixture Screw OUT a few Degrees more until the BLUE fades-out.

This additional Richness is a very slight adjustment.
The width of a Nickel or a Dime.

Imagine a Stop Watch.
One minute is 60 Seconds.
15 Seconds = ¼ of a Turn.
The additional Richness is but 4 -to- 6 Seconds.

 

Re: I cannot adjust the idle screw after i cleaned carburato

The IDLE Adjustment Rod should be set to a point where the Number-3 Carb is closed on a Strip of 3 X 5 Card, Business Card or a Narrow Strip of 35mm Film. (quote)
You missed the point Rick, you must have the idle adjustment midway on the thread, then start the bench sync.

 

Re: I cannot adjust the idle screw after i cleaned carburato

Actually you don't. Since a bench sync is done with the butterflys nearly closed the idle rod can't be midway on the thread. There'd be no point to having more adjustment on the idle screw in that direction. Once the butterflys are closed they can't close any further.

 

Maybe a good idea to check throttle cable adjuster and cable routing to ensure its not snagged anywhere..?

 

Don't argue with me, moe, you'll come second.

 

The Idle Adjustment Rod controls the Position of the Number-3 Carb.

If the Idle Adjustment Rod is "Mid-way" the No.-3 Throttle will not close enough to allow the Rack to be "Mechanically Syced".

In effect, ... the Idle Adjustment Rod is the Sync Screw for No.-3

The precise adjustment of the Throttle Plate of the No.-3 Carb is done by adjusting the Idle Rod.

 

Be an adult and explain what your reasoning is, instead of acting like a 12 year old.

http://xjbikes.com/Forums/viewtopic/t=6366.html

 

Re: I cannot adjust the idle screw after i cleaned carburato

Oh to be 12 again ;o(
Firstly don't take everything Rick says as gospel, he has been wrong before, more than once.
If you, like so many other members, have bench syced, then done a running sync' only to find that there is not enough thread on the idle adjusting screw to fully close the butterflys, then you may realise that there could be more than one position for the I A S vs #3 butterfly at the start.

 

The Idle Adjustment Rod Opens and Closes Number-3, alone.
But, ... 1, 2 and 4 simply go-along for the ride.

When the 3-Carb gets Closed by turning the Idle Adjustment Rod counter-clockwise there is --> NO further adjustment <-- to be made by additional turning of the Adjustment Rod

There is --> NO "Preset" <-- of the Idle Adjustment Rod.
When the Threaded-end of the Idle Rod fully disengages from the Linkage Platform on the 3-Carbs Linkage, when that Rod is turned-out, ... that's it.

 

Re: I cannot adjust the idle screw after i cleaned carburato

Closed is still closed. Setting the idle speed screw to mid-thread will always lead to the throttle plates being partally open; perhaps more open than necessary. Your method simply adds a step where none is needed.

The OP's problem sounds like he either dosen't have all the butterflies synched (one or more are slightly more open when #3 is closed), or there is a vacuum leak (likely at an intake boot).

 

this is so simple it's hard to describe
turn in the idle knob till #3 moves then 4 more turns.
A) turn the 1/2 screw until 1&2 look even
B) turn the 3/4 screw until 3 &4 look even (only 4 should move)
C) turn the 1/2 - 3/4 screw until those two sets look even.
D) back off the idle screw one turn
keep doing A thru D until the idle knob will let all of them close at the same time.
turn the idle knob until it just touches, then 1 full turn in, your done.
forget the YICS, forget you know about it

 

It's true.
I have been wrong more than once.
For the sake of the argument, ... let's say ... oh what shall we say?
How about a dozen times. 12. No, ... 13. A bakers dozen.
Oh, ... what the heck.
Let's call it an even 50!!!

50 times in 13,780 posts.
That's
0.036 of One-Percent!!!

100 would still be shy of 1.0 Percent
72 Hundredths of one percent.

I think I know my way around Hitachi CV Carbs and Mikuni's too.

Seventy-two hundredths of one percent.
I can live with that.

And, ... I'm sure a couple of those times I was wrong, ... were when I said I was wrong, ... and I wasn't!

Now-a-days, ... I just keep an eye on things.
You need advice???
Ask Fitz!

 

51 times, check your math

 

Re: I cannot adjust the idle screw after i cleaned carburato

If only I could be as coherent in my elucidation as you are Polock.