rejet help carpy 4 to 1 1977 cb750

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rejet help carpy 4 to 1 1977 cb750

hutchman08
Hello all,

I have a 1977 CB750 4k with carpy 4 to 1 exhaust running with stock air box.  I kept the same jetting which is the main jet at 115.

The problem I have is that when I try to 1/8 to 1/4 turn the throttle the bike stalls out.  I experimented with the idle screw and can only get the bike to idle around 1,000 RPM.  Is this normal?
I covered the air box intake with tape and the bike did not bog down and I was able to have the bike idle around 1500 RPM.
The bike also would not stall out when I turned the throttle 1/8 to 1/4.   All help greatly appreciated.  thanks again.
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Re: rejet help carpy 4 to 1 1977 cb750

TOOLS1
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1000-1100 RPM is where these bikes idle at. How did the bike run before you put the crapy exhaust on? Exhaust changes rarely require jetting changes. However what you are describing sure sounds like a vacuum leak though.
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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
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