idleing issues

[janousek_21]

Hey guys im new to this forum. i just bought a 1980 cb 750c. it wasnt running so i pulled the carbs and cleaned them and replaced the plugs. The bike ran but would not idle right. i adjusted the main idle srew and got it to idle but as soon as i would rev it up the idle would spike and stay at about 4000 rpm for awhile. also when i leave the gas on gas  flows out of the bottom of carb number one. dont know much about these older bikes so any help or suggestions i could get would be great!

thanks

[Re-run]

Your carbs are not clean. The fuel flowing out of the carb bowl indicated the float needle or seat are dirty.
The idle could the that the screw is turned in too far to compensate for a dirty idle circuit, that there are cracks in the carb boots, or both.
You will want to get the manual here and go through everything in the carbs. Do not just spray them, take out the jets and clean them with copper wire strands. Use a qtip on the float needle seats.

Make sure you also have a tank filter or an inline filter for gas. Dirty gas will nullify any cleaning you do.

[dave Esch]

My carb leaks if I leave the petcock on also. I figured this was normal for these old bikes so I just shut the fuel off when I park it. I hate it! I always forget to turn it back on. You know what happens next!

[janousek_21]

hey thanks for the info. i am going to mess around with it this weekend so hopefully i get it running good.  do you recommend presetting the carb adjustments 1 and a half turns out to start like my book says? and yeah i shut mine off too but it still leaks out bad when its running as well. real annoying and waste full at 4 bucks a gallon!

[Re-run]

Does it leak after the valve is off? If so, then the valves needs cleaning or replacing.

[janousek_21]

No it quits leaking. i just replaced the petcock not to long ago cause it was leaking out of the switch itself.