1980 custom. High idle when cold/first start up

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1980 custom. High idle when cold/first start up

Ganguskahn91
I have a 1980 cb750 custom and have been working on it for a while. I'm new to this so bare with me lol
I just took apart all four carbs, and found I had a air fuel mixture pin (pretty sure that's what it is) missing, so got a new one and screwed it in till I felt the spring touch. When I put all the pieces back on the carbs, I just tightened it up and thought nothing of it. When I plugged the carbs in and started it, it was idling at 5k and I could do nothing to bring it down. I checked the idle screw and screwed it out all the way, but no change. I unhooked boy of the throttle cables, and still no change.
Could my problem be inside the carbs? Like the flaps?
Thanks in advance!
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Re: 1980 custom. High idle when cold/first start up

seestheday
Are you sure your high idle screw is turned all the way down?  They can bind and feel like they're all the way out but aren't really.

If it is, then there is a good chance you have a vacuum leak.

Did you screw in all of your air/fuel mix screws all the way?  If so, the bike shouldn't run at all because no fuel should be able to get in through the idle circuit.

When you say you took apart all of the carbs, did you follow either Randakks or MacGregors's manual?  From your description of things I'm guessing you didn't.

When you say flaps, do you mean throttle and choke plates?

Since you separated the bank, did you make sure that the throttle and choke plates smoothly open and snap shut when released after you put the carbs back on the rail?
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.