Topic: Carb throttle stop screw non existent?

[Jon T]

Hello all this has got me baffled. Upon a lot of research I still cannot figure it out. All the manuals I look at and parts fiches show the throttle stop screw. I am going to sync and tune my carbs on my CB750k3, but there is no throttle stop screw. There is the hand screw that sets the idle for all the carbs but each carb does not have its own screw.
That is a picture of my carb.

All these show a throttle stop screw.
This is also referenced in a previous post.
http://forums.sohc4.net/index.php?topic=144858.0
He shows that CMS has two different fiches, and one has it and one does not. Mine do not. How would I go about vacuum syncing them now? Or am I not looking in the right location? Thank you all for your help

[flybox1]

You dont need a throttle stop screw to vacuum sync carbs.  Its got nothing to do with vacuum sync 
The throttle stop should be between #2 and #3 carbs...

[Jon T]

That's the throttle stop for all of the slides. In the diagrams, #2 in the first and #20 in the second. Maybe I am incorrect, then what do you adjust when you vacuum sync? The air screw? That doesn't sound right to me


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[flybox1]

you adjust the vacuum sync screws located between the carbs

also...why do you have a JET (with a hole in it )in your vacuum sync tool hole?
(Brass jet right under your choke lever pictured above)
 that needs to be plugged unless you have your vacuum sync tool attached.

[Jon T]

It's referenced as a throttle valve stop screw


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[Jon T]

Hmm I thought a plug went there but when i rebuilt them that's what it had on and the kit had a new one so I used it.


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[Jon T]

Also there is no screw for me to adjust between the carbs. Where would this be located exactly?


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[flybox1]

#1 is your idle mixture screw.  it controls air into the idle circuit
#2 is your vacuum sync port.   you attach your vacuum sync tool to it when performing a vacuum sync.  It SHOULD have a solid brass screw in it at all times.  your #110 jet doesnt even go there....take it out and put the proper screw there.  See fig 6-16 above
This is a picture of your #1 carb....your throttle stop screw is on your #4 carb....in the hole marked #3 for reference.

See fig 6-16 in your pictures above....thats the #4 carb....and #1 listed in this response is solid brass...not a jet

[Jon T]

On my #4 carb it is the same as my #1. Just an empty hole with nothing in it that doesn't have any threads. I appreciate all of the help though, trying to figure out what the problem


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[flybox1]

the screws you adjust to vacuum sync your carbs are located on TOP of the carbs....under the black plastic boots.

[Jon T]

And you believe I have the plug in the air screw hole?


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[Jon T]

I have a nut and lock nut underneath the boots, but it's the same concept I guess. I will adjust it by that. Thank you so much for all of your help. I'm surprised the bike ran like this


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[flybox1]

Im surprised too as the air allowed in throuh your 110 jet in the vacuum sync port would make your bike run really lean.

in my picture above with the red numbers...
your #1 is correct.
#2 is incorrect.  Put a brass screw in there


This may offer some help...same carbs.

[harisuluv]

If you put the main jet in the vac port, what is currently being used for the main jet?