RPMs race when choke is off

[Endline1977]

Hello all, i just pulled my grandfathers 1976 Cb750f out of storage. It had been sitting for about 10 years and the carbs were filled with sediment to the point i had to take them to a shop with a parts cleaner to get them taken care of. Once they were back together and on the bike i was able to start it right up and it ran great with the choke on. As soon as it gets warm and i try to shut the choke off the motor just starts revving up close to the redline. I either put the choke back on or kill the bike to stop it. I put the carbs back together myself and adjusted the slides down as much as i could. I am stumped with what the next thing i should look at. If anyone has any suggestions it would be greatly appreciated. Thank you all for your time.

 

[Stabler]

If the bike is stock (stock air filter and stock mufflers) your needle position should be in the middle slot.
As for the revving, I'd say your idle sircuit is running lean (or you have an air leak at the intake rubbers).
Where are your idle screws at? How many turns out in quarters calculated? (Roughly?)
I assume you've checked your timing and your valves are adjusted by the book?

 

[Stabler]

Oh - and is your carbs synched? (Bench-synched anyway?)

 

[CB750Todd]

I would venture to say there is a vacuum leak at the intake boots or something like that...keep searching,you'll get it figured out!

 

[Endline1977]

Ok cool. Thanks Stabler and Todd, i'm currently finishing up my final week and exams at college so i have to stay out of the garage for a while but ill try to figure it out as soon as i button my education up for the time being. I did bench sync my carbs and am waiting to borrow a vacuum gauge from my buddy. ill check the timing and the idle screws i think they are the recommended setting because i haven't touched them and the bike supposedly ran well when it was put away. (i think its supposed to be 1.5 turns out) but I'm not sure where they are, my bike is at my parents house so i cant check right now. The needles were in the middle slot. Ill check the timing and valves too when i get a chance but it seemed strong when it ran but this is the first bike i have really gotten into so i could be wrong. I think that the boots are a good place to start though, it sat in a shed for about 10 to 15 years but i think the last time it ran was 10 years ago. Ill keep you all informed when i chase it down ill let you know. Thanks again for the advise.