Topic: Low manifold Vacuum on '77 CB550k

[RatFink84]

My bike ('77 550k, pd46a) is giving me a hard time. It does not want to run without the choke all the way out and won't idle at all. It has a real low manifold vacuum as well

Things Checked
- Valve Clearance
- Cam Timing
- Ignition Timing and points
- Carbs bench synched
- Compression check
- used an automotive smoke machine to look for leaks in the intake manifold
- Cleaned out all passageways at least 5 times now.
- Checked spark
- Float levels set to 14.5

I do not know where to go from here. Any suggestions would be greatly appreciated.

Thanks
RatFink

[Gordon]

Air filter?  You running the stock air box or pods? 

[luap]

how bout the rubber intake booties any cracks also the 4 small screws on the intake manifold all those tight

[d9canada]

Chances are real good that your carbs need all the slow speed circuitry cleaned out.  That's usually the reason why it will only run on choke.  It would be good to check your output from the tank, incase the petcock screen is plugged, use an inline filter, and then do your carbs.

[RatFink84]

It is running pods and the fuel delivery to the carbs is fine, since we're using an IV bottle for gas. I have sprayed wd40 around the carb boots with no noticeable change and tightened the synch port screws.

[Gordon]

It is running pods and the fuel delivery to the carbs is fine, since we're using an IV bottle for gas. I have sprayed wd40 around the carb boots with no noticeable change and tightened the synch port screws.

Have you re-jetted to compensate for the pods?  If not that would explain why it needs the choke to run. 

[RatFink84]

Up to 105 from 90. Do you think that is sufficient or should I go up? It also has a 4-1 hooker exhaust system.

[Gordon]

I don't do pods so I can't say, but check some of the other pods threads to see what others are running. 

[Danno]

you will need 40 slow jets and 110 to 115 for pods probably 115 mains your mains are too small and probably your slow jets too plus I would move the needles up if the pds have them you move the clip down to move the needles up only do one notch