adjusting cv carbs???

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adjusting cv carbs???

slownugly007
Hey guys its bee a long time since Ive posted, hadnt really messed with my bike much.

I finally got my carbs cleaned up and put back together with the new 75 and 110 jets with K&N pods (as suggested per Deuces Wild DOHC). I removed the vacuum assisted petcock and bypassed the air cutoffs and turned my pilot screws out 3 1/2 turns (Also, standard upgrades per Deuces Wilds site). The bike started up great and super fast, but after a few seconds it revved up really high and continued to climb. I pulled the choke out and got it to calm down a little and adjusted the high idle knob....not sure if this was the correct approach??

The carbs were bench synced, to the best of my ability, so I believe they were fairly close, but i could be wrong? Im waiting on my sync gauges to come in before I can sync them up right....but wasnt sure if I could at least get it close enough to test ride it with the new jets and pods?
 
Ive never adjusted these carbs before so Im not entirely sure what needs to be adjusted or if one thing needs to be adjusted before the other?
Hopefully someone can point me in the right direction and help me understand what I need to do and why? If anybody has any light they can shine on this it would be appreciated! Thanks guys!!
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Re: adjusting cv carbs???

SoonerRon
High idle is usually a sign of a vacuum leak. The rubber insulators are notorious for getting hard and cracked. Check the insulators for leaks using starter fluid or some other flammable spray. If there is a leak you should hear the engine increase in RPM briefly as the starter fluid is sucked into the engine.
1979 CB750K
1978 CB750 Four SS (gone but not forgotten!)
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Re: adjusting cv carbs???

SoonerRon
Also, Check your choke cable to ensure it's adjusted correctly. After my last revbuild I had a high idle that was caused by my choke cable being too tight. I increased the play and the idle went right down.
1979 CB750K
1978 CB750 Four SS (gone but not forgotten!)
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Re: adjusting cv carbs???

slownugly007
what should the choke cable be adjusted to? I have it with the choke knob pushed in the choke plates are wide open and when I pull it, it closes the choke plates....is this correct? I sprayed the boots with wd-40 last night (not sure if wd-40 is even flammable, now that I think about it!??)
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Re: adjusting cv carbs???

SoonerRon
WD-40 probably won't work. You need something more volitile and flammable. As far as the choke cable goes, there should be no tension from the cable at all on the choke linkage when the actuator is pushed in all the way. In my experience a little slack in the cable is better than too little
1979 CB750K
1978 CB750 Four SS (gone but not forgotten!)
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Re: adjusting cv carbs???

slownugly007
awesome thanks! I got it to where it idles lower, but still not perfectly. Apparently the carbs werent seated all the way and the choke was a little too tight. But now my problems have changed....the bike will start up and idle but when I put my hand on the end of the muffler the pressure coming out is slim to none...which seemed odd to me, almost as if the exhaust isnt flowing out, plus the down tubes are getting REALLY hot.

Ive never adjusted these carbs before so Im not entirely sure what adjustments need to be made?
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Re: adjusting cv carbs???

Lucky 1
In reply to this post by slownugly007
You cannot bench sync CV carbs.
The slide is vacuum operated, it is not controlled by a cable.

The butterfly in the intake can be adjusted so that all of
the butterfly's ( on the engine side of the carb) should start to open when you turn the throttle.
They should start open at the SAME time -as soon as you start to open the throttle.

Make sure all of the butterfly's are closing ALL the way!!

The idle is controlled by the butterfly cut out .

On a Roadstar Adventure.
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Re: adjusting cv carbs???

seestheday
You can bench sync CV carbs so they're close enough for a test ride.  I've successfully done it twice so they were perfectly in sync.  I didn't need to make any adjustments when I hooked up my carbtune sync tool.

If you split the bank when you cleaned the carbs then there is a very real chance that the butterfles aren't lined up correctly.  If this happens they tend to stick and it will give you all sorts of problems.  Like Lucky and others say, they must close all the way.  They should snap shut.  If they don't you have to remove the carbs and loosen/retighten the support rail until they do.
1981 CB750K with 900 cams
90K KM's, rebuilt head, rebuilt carbs, upgraded valve stem seals

My wife's recipe website that I'm trying to help promote: Strawberries for supper. Yes, I am a lucky man.

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Re: adjusting cv carbs???

slownugly007
When yall say they need to be completely closed do you mean that when the throttles closed the throttle plates need to be completely sealed? I was under the impression that I adjusted the flaps with a slight gap in them the size of the e-string wire? Am i way off?
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Re: adjusting cv carbs???

Lucky 1
What does the workshop manual say?
On a Roadstar Adventure.
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Re: adjusting cv carbs???

seestheday
In reply to this post by slownugly007
Mine have that e string gap and then run beautifully.

Sent from my BlackBerry device

From: slownugly007 [via Honda CB750'S]
Sent: Thursday, March 21, 2013 11:06 PM
To: seestheday
Subject: Re: adjusting cv carbs???

When yall say they need to be completely closed do you mean that when the throttles closed the throttle plates need to be completely sealed? I was under the impression that I adjusted the flaps with a slight gap in them the size of the e-string wire? Am i way off?


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NAML

1981 CB750K with 900 cams
90K KM's, rebuilt head, rebuilt carbs, upgraded valve stem seals

My wife's recipe website that I'm trying to help promote: Strawberries for supper. Yes, I am a lucky man.

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Re: adjusting cv carbs???

taylormade198002
In reply to this post by slownugly007
http://www.cb750c.com/publicdocs/SeanG/Honda_Carb_Manual_revE.pdf



maybe this will help....
1982 cb750 custom
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Re: adjusting cv carbs???

Lucky 1
A must have link for those with the DOHC carbs!
Excellent !
On a Roadstar Adventure.