Rebuilt CB750F revving out of control

[MrMontombo]

I recently purchased a rebuilt 1976 CB750F and everything was running good. Then today I tried to drive it to work, was going down the freeway, when I let go of the throttle and the bike wouldnt slow down. I pulled in the clutch and it started revving out of control. So I hit the kill switch and pulled over. Now every time I start it it revs out of control without any application of the throttle. I checked the throttle, it seems fine. It's pulling in and out of the carbs seemingly ok. I not sure what to look at next. It is currently sitting on the side of the highway until after work when I can get a truck.

 

[dirtdigger]

first you need to look for leaks in the intake boots...either loose or cracked. Then make absolute sure that the throttle is closing all the way....see if the throttle is actually touching the idle stop screw. It doesn't take much throttle opening to make the motor rev high under no load.

 

[MrMontombo]

Well I figured out the problem. The guy who bIke put a piece of a beer can in each air intake to slow air flow. That can got sucked into the throttle. I feel silly now. Thanks for the help

 

[dirtdigger]

That is absolutely scary. Glad you got it figured out before you got hurt. Do it right and start the process of jetting it correctly. There is no reason to restrict airflow, all you are doing is losing power. See what you got for main jet size.