Topic: 78 cb 750k carb question

[bultaco59]

Hello gentlmen, I know Im asking alot of questions,this being my first sohc 4
Ok heres the deal, I gots carb apart, and there ready to soak, when I took them
apart, there is this big diafram, with linkage that connects to the main shaft
with hoses that connect to the carb, and to this switch of some sort that has
electircal connections (2 wires)that plug somewhere on the wiring harness.
1. What the hell is it ? 2. Do I need this. on reasssembly I would like to leave
all of this off, I m guessing its smog stuff. has anybody seen this stuff. I sorry
theres no pictures, but Im at work.

Thank You
Bob in Burbank

[bultaco59]

Hi guys, well I think I figured it out, I also think I might be f'ed, maybe not,fingers crossed !!
these carb are off a 78 cb 750 A model I've posted a diagram of what I was trying to explain
early, question: can I remove all of this stuff, none of it is on the k model. any thoughs ?? before
I go further I need to know what Im working with. thank you so much for the help.
learning the hard way. its all good.

thanks
bob in burbark

[TwoTired]

Why are you using auto carbs?  Do you have an automatic?
As I understand it, the carb throats are smaller, and jetting is different from the standard K variety PD carbs.  Are you experienced in the rejetting process?

I'm not sure, but have you checked to see if they will fit on to your existing carb couplers.

What sort of custom machine are you building?

[raymond10078]

Yep - that diagram is for the auto bike.

If that's what you've got, the carbs DO have smaller throats, and require carb holders that are no longer available (different than the K bikes stock holders).

For the auto bikes, going to a K bike carb is a performance upgrade - so you'll be going backwards here . . . unless you've got some unusual project going.

[seanbarney41]

I don't think you would want to use those carbs...I had no idea the auto's used such a contraption...it looks like an electric choke of some sort?...in conjunction with an accelerator pump?  Was the bike running before?  any good?   I would keep my eyes open for a set of the correct carbs in rebuildable condition, here, or on ebay, or a junkyard.  I don't know much about the 77-78k carbs, but there are plenty of others hear that do.

[seanbarney41]

dude...I seriously posted in your thread and immediately saw this...
http://forums.sohc4.net/index.php?topic=117523.0;topicseen
I think pd41's are what you should have?

[bultaco59]

Hi guys, thank youfor the info, I bought these on ebay, my fault !! I DIDNT MY HOMEWORK, I didnt there was a difference. holy #$%* I know now. so PD41 it is, back to hunt , well I will keep you posted. thanks again for the help.
 

Bob with his tail between his legs in burbank.

[bultaco59]

Hi guys new/used set of carbs on the way, clean and rebuild when they arrive,
I will be installing motor, then carbs, new four into one, and pods, jets for this set up ? to get it running good enough to get it to the shop, where they will adjust valves,time, sync carbs, tune up. then I can start on my cafe project. I will keep you posted.

bob in burbank