Topic: Kei Hin carb question, noob-ish, please be kind!

[Reganator]

Ok, I'll spare you the details of my lack of experience with carbs, I'm fairly knowledgeable of mechanical whatnots otherwise.  I swear it.

In any event, I am learning and begining a rebuild on some carbs for my 71 CB750.

Being the inquisitive type and trying to learn about these things, I've noticed that when the choke is activated the slides rise and the doors in the slides remain closed, save the one for the first cylinder, which is opened by spring.  It would seem that maybe all 4 doors should open, or maybe just the first?  Or maybe none?

Well?  Any suggestions on which?

[kghost]

If memory serves they should all be closed and are opened by vacuum on all 4

[ekpent]

Do you have a picture of those carbs. The 71 750 does not have any high idle circuit in the choke so the slides do not move with the handle on the side of the carb rack. When the choke handle goes up the 4 'doors' come down in the throat to create choke,all at the same time. Its a really primitive system. If your carbs are unmolested 71's they should have brass floats,changed to plastic in later years.

[phil71]

ekpent is right.. what you describe should not be possible on a 71

[harisuluv]

I think he is referring to the chokes as "slides". Pictures would help us to understand. Regardless, they should all be acting the same way in each carb. 

[Bodi]

All should be the same. The choke plates should swing open and closed pretty much the same, I set them so all are open with choke off and whatever that works out to with choke on. There are small holes in the choke plates with little trap doors that should be held closed by tiny springs: these open under engine vacuum to help avoid flooding. It is probably no big deal if one of these springs is broken so the trap door stays open. The actual throttle slides will rise slightly when the choke is on to raise the idle RPM so the engine doesn't stall out when really cold.

[phil71]

the throttle slides raise? On those cars? You're thinking of PDs I think.

[bollingball]

Ok, I'll spare you the details of my lack of experience with carbs, I'm fairly knowledgeable of mechanical whatnots otherwise.  I swear it.

In any event, I am learning and begining a rebuild on some carbs for my 71 CB750.

Being the inquisitive type and trying to learn about these things, I've noticed that when the choke is activated the slides rise and the doors in the slides remain closed, save the one for the first cylinder, which is opened by spring.  It would seem that maybe all 4 doors should open, or maybe just the first?  Or maybe none?
Well?  Any suggestions on which?

never heard of a door on any of these carbs look at a part diagram so you know what to call what so we don't need a translator. Yes pictures will work

[flybox1]

the throttle slides raise? On those cars? You're thinking of PDs I think.

+1
sounds like PD carbs.

[lucky]

What year is the motorcycle #1?

[Reganator]

Thanks for the help so far gentlemen.  I was expecting a certain degree of hooting and hollering, and I appreciate your candor.

Anyway, on to the info.  This is a 71 CB750.

As for the pictures, I have a few. 

Go to imgur and add "/a/xhI5V" to the end of the web address.

Sorry for making you copy and paste, I am "not allowed to post external links" for some reason.  If you are interested, I also have a site I'm using as instructions for the cleaning that gets fairly in depth with my carbs.

The first is just the carbs in question.  The second is the open door, and the third and fourth show the doors closed on one of the other carbs.  To be clear, only the door on the first cylinder is open, the rest are closed.  I don't know if you will be able to tell in the first image, but the door has a spring that is forcing it open while the others remain closed.  Again, any advice would be greatly appreciated!

As for looking it up in a parts diagram... well... I'm trying, but that remains elusive.  I'll keep trying, hopefully the pictures are enough.

[ekpent]

Make a couple more posts,think you need 5 or so then you can post pics easily.