Topic: What worked for my 1977 CB750K with pd41a carbs.

[Paintedseat]

Ok these carbs seem to give their owners some trouble. I am just going to post what I did to mine because it runs great finally! I have stock airbox and a MAC and 4 to 2 exhaust. I have 38 pilot jets. 115 main. The needles are on the 4th slot. One important detail is to make sure you accelerator pump rod is in contact with the arm. It runs amazing and I can't believe it's the same bike I have been working on. It pulls all the way to 8k hard.

[Mr. Mike]

My 78 CB ran really well too...once warmed up. 100% stock
Took about 3 miles before it would idle fine (choke open) and I wouldn’t have to worry about a stall at the signal light. Replaced them with a set from a 74 CB750 and appreciate the difference.

Glad you got yours sorted out.

[Paintedseat]

No warm up time needed. I choke to start choke for about 2 minutes choke off. Runs great from the get go.

[Erny]

One important detail is to make sure you accelerator pump rod is in contact with the arm.

what do you mean by that? Any photo?
Sorry for the question, I plan to clean/rebuild carbs too (K7, PD41A)

[Paintedseat]

The metal rod that goes up to the top of the carb. There is a arm that pushes the rod downward when you twist the throttle. You want the arm to activate or start pushing the metal rod as soon as you start twisting the throttle. It should be touching or at least within a mm. You can bend the arm if needed. I don't have a picture I should have taken one.

[BobbyR]

One important detail is to make sure you accelerator pump rod is in contact with the arm.

what do you mean by that? Any photo?
Sorry for the question, I plan to clean/rebuild carbs too (K7, PD41A)

On my 78K there was a good sized gap between the tab that actuates the plunger and the plunger rod. You simply bend the tab gently until it touches the plunger rod. This squirts some gas into the carbs instantly when you twist the throttle.
Very simple and gives you good response. I use the choke until I clear the stop sign at a bad intersection at the end of my street, push it in and ride it to do the warm up.