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I have cleaned and rejeted the carbs to 145 mainjet. I have straight pipes 2 into 1 on each side and cone air filters. If I close idle air screws and adj the locknut on the carb should it be able to run with the choke off?
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Administrator
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I'm not sure what, you are asking, but I think the answer is no.  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)
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the bike will run with the choke on, but as soon as I touch it to turn it off it the bike dies out.
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Administrator
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Your pilot jets are plugged up.
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)
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Don't tell me I gotta pull these carbs and clean them again
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Administrator
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You could just sit on the bike, and make engine noises. Worked, for the mouse in my grandbrats story book.  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)
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thats all Ive been doing since I got the bike lol,
what could be clogging the pilot jet? could I run some seafoam through it and hope it clears it up?
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Administrator
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145 sounds like an awfully big jet. I have similar exhaust and air cleaners I am running 125 mains and 42 pilot jets.
I agree with tools an the pilot jets. Your bike is not getting fuel thru its idle circuit,having the choke on is just richening the mixture and masking the problem.
You CAN get to the jets to clean with the carbs on the bike. The pilot jets are VERY fragile so doing it on the bike makes it very risky. When I was tuning my carbs and swapping jets there was no way i was gonna pull the carbs off every time. You can just pop the bowls off and get to it. You will need either a perfectly sized stubby or a right angle screwdriver.
It can be done on the bike but be VERY CAREFUL! Try cleaning the pilots.If that doesn't cure it you may have to pull the carbs and resoak/clean them.Or you could try running a small wire thru the jets with them still in the carbs and see if you can get any debris out. Much safer for a first round test.
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Thanks ribs- what year bike do you have?
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Administrator
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This post was updated on .
Mine is a '76 Super Sport .I have the same carburetors as you and our engine are almost identical,if not identical.The differences between your bike and mine are extremely minimal. I am not a bike mechanic.I have only had my bike for about 6 months now and its my first. The guy who runs a local bike shop near me loves old jap bikes of all types. I used his advice on tuning mine and it worked out great. My bike runs faster and uses less fuel than anyone will believe.But regardless of all that,it has been reliable. Thats the main concern. I dont suppose you live nearby me. If you are anywhere near SW Virginia I would be glad to give you a hand.
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Im actually in Beckley WV which is not that far from you. this bike is a completely new learning experience for me. Im hook on it though.
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Sorry, I'm confused. Did you close the air screws all the way? I'm not familiar with the SOHC carbs, but that sounds wrong - I'm sure Tools or Shiny would know better.
Or are you referring to the idle adjuster? Closing that all the way also sounds wrong.
On the DOHC carbs, only the carb sync screws have a lock-nut. If you were closing those all the way then your carbs would no doubt be horribly out of sync.
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.
My cb750 video site
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A little off topic but I've been wanting to get an opinion on how these bikes sound with straight pipes, and if i should go with 4 straight pipes or 4 into 2's like yours. Youtube videos don't cut it so how does your bike sound?
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Administrator
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My bike had two pipes down each side before. It had a real nice deep throaty sound to it.Tools has those now.
 The 4 into 1 I have now has more of a performance sound to it. Kinda zingy sounding if that makes any sense.
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Administrator
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On my bike the idle air adjustment screws ( is that the right name?) ended up on 1 1/2 turns out.
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I really want that chopper sound if I can get it, have heard some of the bikes on youtube that sound good with 4 smaller pipes, but none with 4 into 2's so I can tell the difference....
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Administrator
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I have video of them running on my phone,but I cannot for the life of me get it off of there. I'll see what I can do.
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Download Google Youtube app, then upload to Youtube. 
Turbos, Hondas, 4-bangers, what could go wrong?
 Shiny: [...] Considering the weather you've had to put up with I'd say you get an Iron Butt award and a Frozen Nipple trophy to go along with it. First time I've ever posted the word nipple... it ends here.
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Shiny, there are 4 air/fuel mixture screws on my DOHC carbs, and one idle adjust knob.
I believe stock on the DOHC is 1 1/2 turns out for all 4 air/fuel mix screws. If you've done anything non-stock like mufflers or pods this will have to be adjusted (and of course you know this). I'm currently waiting for a 90 degree screwdriver to arrive in the mail before I can properly tune my air/fuel ratio.
Idle adjust knob was just turned until I got the idle to where I wanted it once the bike warmed up.
Doing a quick search it seems that the SOHC's have an idle adjust knob as well.
Also, I'm not 100% sure if I'm calling them the right names. If anyone knows, please chime in.
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.
My cb750 video site
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Thanks Shiny for the help again
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Locked
