Vintage and Classic Hondas

Not able to open throttle past half

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IrishBastard85
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Not able to open throttle past half

IrishBastard85
Hey guys, this is my first CB750 experience so bear with me. I have a 76(I believe) SOHC engine with 086A carbs, open header exhaust and filter pods. I recently rebuilt the carbs and had planned to re-jet because I could not open the throttle past half with out the engine stumbling to the point of stall. Once I torn into my carbs, I found it has 125 main jets, and stock (40s) slow jets and the jet needle set at one notch above the bottom.  I set the jet needles to the bottom notch and it seemed to run better, although I still can't open the throttle much past halfway without lots of black smoke, and horrible fuel smell. What am I missing? Points at set at .015 and I'm getting good spark.
76 CB750 hard tailed and raked. III% http://ruffneckresistancermm.com/
TOOLS1
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Re: Not able to open throttle past half

TOOLS1
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You are too rich. Try going the other way, and start leaning it out.
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Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
I like vintage bikes because they take me away from the clutter of technology that I work with everyday and back to a simpler time of mechanical elegance and simplicity.. "ninadm"
Darkwing Duck: The worst part of public transportation is the Public.
"That is awesome shit there" Re-Run
"Fear nothing, attack everything" Eric Berry
" Oh, you read that on the internet? Clearly it IS a massive problem. Of course it CAN’t be normal operation."

1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)
IrishBastard85
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Re: Not able to open throttle past half

IrishBastard85
I set the needles at the middle setting, factory I believe. I have more than half throttle now but still starts cutting out at around 3/4 now. I'll keep playing with it.
76 CB750 hard tailed and raked. III% http://ruffneckresistancermm.com/
TOOLS1
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Re: Not able to open throttle past half

TOOLS1
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Try a 120 main.
TOOLS
Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
I like vintage bikes because they take me away from the clutter of technology that I work with everyday and back to a simpler time of mechanical elegance and simplicity.. "ninadm"
Darkwing Duck: The worst part of public transportation is the Public.
"That is awesome shit there" Re-Run
"Fear nothing, attack everything" Eric Berry
" Oh, you read that on the internet? Clearly it IS a massive problem. Of course it CAN’t be normal operation."

1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)
IrishBastard85
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Re: Not able to open throttle past half

IrishBastard85
Do you think if I fab up some baffles or go with a longer pipe would help?
76 CB750 hard tailed and raked. III% http://ruffneckresistancermm.com/
TOOLS1
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Re: Not able to open throttle past half

TOOLS1
Administrator
It would if you were too lean, but you are too rich.
TOOLS
Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
I like vintage bikes because they take me away from the clutter of technology that I work with everyday and back to a simpler time of mechanical elegance and simplicity.. "ninadm"
Darkwing Duck: The worst part of public transportation is the Public.
"That is awesome shit there" Re-Run
"Fear nothing, attack everything" Eric Berry
" Oh, you read that on the internet? Clearly it IS a massive problem. Of course it CAN’t be normal operation."

1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)
Re-run
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Re: Not able to open throttle past half

Re-run
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In reply to this post by IrishBastard85
How many turns out are your air screws? In=richer, out=leaner. MIght be something to look at to further tune your idle and midrange.

I would check your current main jets and see if it has been drilled or if the emulsion holes on the sides have been enlarged. A 125 doesn't seem like it should make things THAT rich. So maybe the jets got drilled.
The ride IS the adventure. The destination is just to get gas!
IrishBastard85
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Re: Not able to open throttle past half

IrishBastard85
The air screws are about 1.25-1.5 turns out, been playing with them today and I set the needles back to stock and I have close to 3/4 throttle now. I was wondering about the jets myself, and how would I know if the emulsion holes are enlarged?
76 CB750 hard tailed and raked. III% http://ruffneckresistancermm.com/
IrishBastard85
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Re: Not able to open throttle past half

IrishBastard85
If I go much further out than 1.5 turns, I get backfiring at idle so I stick around the 1.25-1.5 turn area
76 CB750 hard tailed and raked. III% http://ruffneckresistancermm.com/
birdmannn101
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Re: Not able to open throttle past half

birdmannn101
In reply to this post by IrishBastard85
Throw those pods in the trash and go get the original airbox.  Been there, Done That...
66 S90
64 C102
65 C100
65 CT200 Trail 90
74 CB350Four
73 CB750K3
76 CB750A
03 VTX1300S
Bicycle with HF engine
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