81 CB750F DOHC SUPERSPORT.

The bike ran great last week....it is a custom bobber and has had a ton of work done to it, but nothing to the motor besides new jets. rode it last week, fine.....all i did different is tape off and paint the motor...without any dis- assembly. now it wont run unless you have the choke out and keep on the throttle....i cleaned the carbs(they were clean as a whistle), and put in an inline filter. no trash coming from the tank into the carbs.....why could be keeping it from running? spark plugs are fine and getting spark.....also runs rough when you do have the throttle open.....like is it starving for fuel.....how could it go from running to not running just like that. i got no paint in the motor.....or in the carbs....

 

if you removed the tank you may have a pinched or clogged breather... it may even be inside the tank

 

breather on the tank? i have a tank on it from a cb360t....but it was cleaned and coated on the inside....and a new petcock.....i have taken the tank on and off 1000 times.....how do i check the breather?

 

gravity tanks are vented so there is no vacuum to disrupt the fuel delivery... most tanks have a tiny hole right around the cap area that vents to the lower side of the tank, this in turn usually has a rubber hose attached to it... either/or COULD BE clogged and /or pinched and you wouldn't know it until you get fuel starvation issues.