Topic: 1977 Carb

[77 CB750A]

I like the older carb without the electric choke. Does anyone know if the earlier 70s model carbs without the electric choke bolt onto the 77 750A?

[raymond10078]

First - there is no "electric choke" on the 750A carbs.  Not sure what you meant to say.

Otherwise, the older carbs don't have accelerator pumps, which are good thing to have - good, but not essential.

[raymond10078]

I thought I'd address the "core" of your question directly.

It is my understanding that all of the SOHC 750 carbs will "bolt onto" a 750A.

[77 CB750A]

Thanks for the replies. I am pretty new to the 750A as I have only had my bike for a few weeks. On this 750A there are two wires that go to the carbs and it was my understanding that these are for a choke or something that adjusts how much fuel is being dumped into the carb based on the timing of the motorcycle. Also, the 750A has smaller carbs than the other 750 models so I was not sure if the other older model carbs would be able to bolt on. 

[raymond10078]

There may be two wires that "go by" the carbs, but there is not two wires that go "to" the carbs.

FYI.

[raymond10078]

My memory switched on - the two wires you are talking about probably go to a solenoid that is mounted alongside the carbs.  This solenoid (with other parts) controls the idle speed.  When in gear, the solenoid opens, providing vacuum to a dashpot that slightly opens the throttle, so that the bike doesn't die in gear.  This system is discussed in the Service Manual available on this site.

[77 CB750A]

Thanks for the last post that is a good explination. So will the carb from a early 70s 750 bolt onto a 77 750A? I know the carbs are smaller for the 750A so not sure if the earlier or non A model carbs bolt on.

[raymond10078]

The rubber isolators/connectors between the head and the carbs differ from the A bikes to the other 750 bikes.  Provided you also swap over these pieces (with the differing carb set), other carbs will fit fine.

[77 CB750A]

Thanks

[Danno]

the carbs on the 750A are exactly the same as the 750 but the jets are a little smaller to be honest i think the 750A that i had was using the same jets as my 74 cb 550 the remember it has a ritchening screw in the bottom of the carb not an air bleed turning it to the left will make it ritcher not leaner like on an air screw stock jet sizes are in the service manual posted here on this site