Topic: CB750 not running right???

[Seyser]

I picked up a 76 750K. This past weekend, I cleaned all the carbs and put them back on but it doesnt quite run right. It starts, idles great but if I blip the throttle really quick it will bog out. If I ease into it, it runs great so just when I twist it quick. Suggestions?

[Rocker]

Is your choke on? I know it's a stupid simple question but I have done it before. Bike idles great and when I go to hit the throttle it almost died. I had just had mine tuned up and could not figure what was going on. Then I looked down at the choke it it was full on...doh! 

[Seyser]

No the choke is off, Im pretty sure it has to be a tuning issue because it runs perfect otherwise. I havent examined the plugs but I took quick look at the points and they looked clean and everything appeared ok there.

[TwoTired]

You know you don't have an accelerator pump.  Unless you run it very rich at idle settings, it's going to wheeze from a snap open throttle.  Any leaness from something like pod filters would cause issues as you describe.  But, then you would have told us about non-stock configuration.

Perhaps you have an intake runner leak(s) between carb and head.  Perhaps you need to screw the air bleeds in a little. 
Perhaps your slow circuits aren't clean enough.

Maybe you emulsion tubes are still plugged?

Maybe you need to vacuum sync the carbs.

Cheers,

[Seyser]

It is indeed all stock. Im pretty sure I got everything clean. sprayed carbs with simple green, pressure washed, tore down removed floats and jets cleaned more, blasted every jet and crevis with the air hose.

I know what you mean about not having an accelerator pump but Im sure this isnt normal, it just bogs right out.

[Gordon]

You need to check the plugs to find out if you have a mixture problem.

[TwoTired]

blasted every jet and crevis with the air hose.

I've found this to be unreliable.  Seeing air move is difficult unless it is really dirty.  And, there are four holes into the slow passages.  I make sure pressurized carb cleaner will visually flow from each hole in the carb body.  Three out of four just ain't good enough.

What Idle screw setting did you use?  Does turning them in a quarter turn help the response?

Cheers,