Topic: Carbs rebuilt now bike runs worse

[kramerre]

i hae a 77 cb750k that i just had the carbs rebuilt on. The bike ran okay before i had the carbs rebuilt, it just wouldnt rev as freely as i would have liked, you had to really ease into the throttle. Now that i got the carbs back from the shop, (ultrasonic cleaned, float needles replaced and float levels set, air screws 2 turns out) the bike idles at 5-6k with full choke, and about 3-4k without any choke, with the idle screw all the way out on the carbs. When i give the bike any throttle, barely a twist or crack it wide open, the bike wants to bog and die. This is with no airbox or pods on the bike, however i thought it would at least respond to some throttle with no air filter. Any tips? I ordered a stock airbox that im putting back on.

forgot to add, as the bike warms up the idle gets higher. Points,timing, and valves were allset to spec by myself also.

[Gordon]

You can't really diagnose, or even know if there actually is a problem, until you have the air box in place with a filter. 

[kramerre]

thanks, i didnt know the airbox made that big of a difference i thought it would at least idle okay without one

[scondon]

The airbox does make a big difference. If you can't bring the idle down with the idle adjuster then I would think one of two things:

Throttle cable adjusted too tight

Carbs are out of synch. I'm of the opinion that carbs should be synched on the bike any time they are taken off and disassembled.

[madmtnmotors]

+1 on the throttle cable adjustment. Choke cable could be set too tight as well. Check all carb cables and linkages for freedom and range of movement.

[Spanner 1]

+1.... need vacuum sync. for sure, but not before installing airbox and filter.

[mrbreeze]

Did the rebuilder at least bench sync them?I agree with doing a carb sync (if the carbs were apart....you know it needs it) but only after making sure everything else is in order and that includes having the air filter installed. If the carbs were put back together properly,you should be golden after a proper carb sync.