85 cb700sc Nighthawk Sport

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85 cb700sc Nighthawk Sport

SoCalMotoClassics
Hi, just joined group.  Recently acquired an 85 cb700sc Nighthawk embargo bike.  From what I've learner it's a de-stroked 750, sold everywhere else as a 750.  Its work in progress, thinking of doing a semi cafe conversion.  I welcome any input or expertise.  Been on 2wheel hiatus for 30 yrs, just got back in and loving it.  Looking for service manuals, prints, schematics, etc.  Thanks, Rick
1973 CL350, 1975 CB750K, 1980 Yamaha DT175E . . . 30 yrs later . . . Picking up where I left off . . . Now riding a 1985 CB700SC Nighthawk S (Fair-weather rider by geography . . . sunny Southern California) . . . Ride to live . . . Live to ride!
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Re: 85 cb700sc Nighthawk Sport

TOOLS1
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Welcome. How about some pictures?
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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Re: 85 cb700sc Nighthawk Sport

SoCalMotoClassics
In reply to this post by SoCalMotoClassics
1973 CL350, 1975 CB750K, 1980 Yamaha DT175E . . . 30 yrs later . . . Picking up where I left off . . . Now riding a 1985 CB700SC Nighthawk S (Fair-weather rider by geography . . . sunny Southern California) . . . Ride to live . . . Live to ride!
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Re: 85 cb700sc Nighthawk Sport

SoCalMotoClassics
So far, I've only done fluids changes, added after market turn signals and replaced levers, getting ready to do a serious going through the bike doing corrosion conteol, rubber replacement where needed, etc.  Next is fuel system including tank, petcock, carbs, etc.  I'm new to the bike mod scene, and some of the mods others do are beyond my abilities, so I will stick to bolt-ons and minor fab.  

Question, can I use synthetic oil?  I read it improves transmission performance, it's a little clunky.  If so, what synthetic should I use for classic wet clutch bikes?
1973 CL350, 1975 CB750K, 1980 Yamaha DT175E . . . 30 yrs later . . . Picking up where I left off . . . Now riding a 1985 CB700SC Nighthawk S (Fair-weather rider by geography . . . sunny Southern California) . . . Ride to live . . . Live to ride!
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Re: 85 cb700sc Nighthawk Sport

TOOLS1
Administrator
Synthetic oil will make the old gaskets and seals leak. Most people use Shell Rotella 10/40 in these old bikes. Very good oil and will not hurt the clutch. If your transmission is "clunky" shifting, you might need a clutch adjustment.
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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Re: 85 cb700sc Nighthawk Sport

SoCalMotoClassics
Really appreciate the advice.  I did an oil change with Honda oil, had heard about Rotella, will give it a try next time. Now to see about that clunky shifting.  Thanks Rick
1973 CL350, 1975 CB750K, 1980 Yamaha DT175E . . . 30 yrs later . . . Picking up where I left off . . . Now riding a 1985 CB700SC Nighthawk S (Fair-weather rider by geography . . . sunny Southern California) . . . Ride to live . . . Live to ride!
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Re: 85 cb700sc Nighthawk Sport

SoCalMotoClassics
Found the service manual for 1984 to 1986 CB700sc
http://paulsnighthawkpages.blogspot.com/?m=1 in a downloadable PDF, kudos to Paul for making that available.  Now all the bits start to make more sense.
1973 CL350, 1975 CB750K, 1980 Yamaha DT175E . . . 30 yrs later . . . Picking up where I left off . . . Now riding a 1985 CB700SC Nighthawk S (Fair-weather rider by geography . . . sunny Southern California) . . . Ride to live . . . Live to ride!