Topic: Carburetor Vaccume Line Routing

[nivlac]

Where do the tubes that are running off the top of the carburetors route to when reinstalling a factory air box? They are currently just hanging down (see pic). I just went through this process with a KZ1100 and the bike was running really poorly until I went back to the factory box. It's carbs had two lines, one running from #1 and another running from #4 and they fed into an emissions valve. I know these are two different animals, but just throwing that out there. I'm trying to get this little bugger running for my son before the season is gone. Carbs are freshly and completely rebuilt, but running erratically and I'm thinking it is due to the pod installed.

[flybox1]

those look like atmospheric vent tubes. 
you can rout them pretty much anywhere, as long as they are not kinked.
Have you completed all of the 3000mi maintenance/tuneup items?
Carbs freshly rebuilt by whom?  Do you know if your accel pump is working properly?

Its not the vent tubes making your bike run poorly, its the general state of tune to the pods you have installed.

[Kenzo1979]

I would just take those vent tubes off.

[nivlac]

I had them rebuilt  by local Harley mechanic. He's pretty competent.  I'm just trying to return the unit to as close to stock condition as possible, and diagnose problems from there.

[flybox1]

One of the shops i get my tires mounted had a SOHC4 CB750 in for service.  Bike still didnt run after being taken to a reputable shop around the corner.  Customer paid $600 for a tuneup/make-run, including a carb rebuild, and it still didnt run.
 When Adrian at my shop started going over this bike, the carbs were filled with varnish and had never been opened or touched.
How can you diagnose if you are not 100% the carbs are right to begin with?  you're taking his word for it.....just sayin' 

check them over yourself.  its not hard.

[nivlac]

No you have point. I'll check them out while I have them off, and repost my findings. Check back when you see this thread. I'll probably have some more questions.

[nivlac]

Pulled #2 apart and found the float bowl and brass whistle clean. Should I be checking the top end/ sliders as I go? I'll be taking the rest of them apart as I get some time in the next couple of days. But check out this pic.

When I drained the bowls #2 had very little fuel in it. And look at the contrast in color. I may have drained part of# 2 the other night when I took the rack off, but I think it was #1 and I stopped because of fuel on the floor.
Any feedback would be greatly appreciated.

[flybox1]

If your slides move freely, and snap back when lifted, there's really no reason to remove them.
the rest of this seems like a lot, but do it and your carbs will treat you right.
use a small wrench and remove the main jets and emulsion tubes they are connected to.
(the big shiny brass thing in the middle)
the emulsion tube will have many tiny holes in it.  make sure they are all clean and free of debris.
use pliers to grab onto and pull out those pilot jets(just below the main jet in the pictures)
they have tiny holes along, and thru them.  get them all spotless.
clean carbs are happy carbs 
set your floats per the book height measurements
you have an accel pump.  take it apart. clean the diaphragm with simple green, not carb cleaner.
it will have micky mouse ears. you'll know what im talking about it when you see it.  be careful to not rip them, but clear them out.  (i usually roll some 100grit sandpaper and gently twist/ream them out)
you'll have a small oring on the top seam of bowl #2, dont loose it.
spray carb cleaner in the hole at the bottom of the bowl, it will spray out where this little oring sits.  its a check valve. it needs to spray well.
there is another check valve in the bottom of the accel pump bowl. spray into the holes along its mating edge to clear out this check valve, too.
note on carb #2...how the bowl fits onto the carbs. there is a tiny hole, where the bowl-top check valve and oring mate to.  this hole is where gas flows to the accel pump squirters.  spray into this tiny hole, and see if carb spray shoots out those tiny brass posts in the carb throats....it needs to shoot well for your accel pump to work well.  any varnish from your bowls washed up into these posts will prevent this system from working.

i just looked again at your first picture.  it looks as though in the past the PO or a mech for these carbs de-racked them, and replaced the rubber fuel tubes with some sort of metal tube?  never seen this before.  maybe bollingball (Ken) will chime in...

[nivlac]

For clarification. Are we talking about using pliers to remove the "slow jet" which my manual says is a press fit and cannot be removed or the can tube that houses the pilot jet screw be removed?
I hope to pick up a parts bike from a forum member this upcoming week and I'll be able to glean some parts off of it. I am hopeful that the carburetors are intact.

[flybox1]

The BIG main jet and emulsion tube is twist out with a wrench.
The smaller pilot jet is press fit and can be pulled straight out with pliers...gentle twist is ok...just don't break their seat...

[750K]

Are these pd's from a cb650?

[nivlac]

Flybox1, that is some real good information,should I hit that with some kind of penetrating lube, PB Blaster or something for a few hours prior to removal?  Yes 750K the bike I'm working on is a cb650 (1979).

[flybox1]

No need.  Just grab and pull. Don't worry about marring the outside of the jet..just don't crush it 

[nivlac]

I got the pressed pilots out w/o much problem they were pretty clean. Another question, the tube that the main jets screw into go over a kind of a needle and as l look at them they seem kind of crusty I took a limp wire and rolled it around the walls and some crusty stuff came out in the palm of my hand. Shouldn't this be cleaned out and if so how would I access them? I don't know if you saw another post that I posted earlier but one of my pilot screws were missing the metal washer between the spring and the o-ring. What would that be doing to the mixture?
My accelerator pump seems to be passing fluid and air easily. The diaphragm and rod are new. Is there a way to verify that it working prior to installation?

[martin99]

Don't make the mistake of flailing around with your carbs, it sounds like they need to be gone over thoroughly and systematically. The carb FAQ has all the information you will ever need and I would suggest you have a good look at that first, as it is much easier to do this task if you have an understanding of what the component parts actually do.

The needle you refer to meters the fuel that comes through the main jet. Some can be moved up or down by clip position but I think you will find they are fixed in your carbs. They shouldn't be dirty, and the crusty stuff you describe is probably old fuel varnish which ideally needs to be cleaned out. Could you be sure that it isn't to be found elsewhere too?

I think the pilot screw you mention is actually the IMS (Idle Mixture Screw). These usually have a stock setting from the factory, depending on which carb you have. Again, the FAQ can help you here. The little washer is there to prevent the spring chewing the little o ring up and to maintain a tight seal.

You can bench-test the accelerator pump by rigging up a temporary fuel supply to the carbs and manually operating the throttle mechanism. You are looking for a strong squirt of fuel into the carbs from each of the posts. I wouldn't worry about that too much yet though.

Sounds a headache, but really not too bad once you get into it. Good luck!

[flybox1]

Nivlac, you can get the needle you found under the main jet by removing the coffin-looking caps which are on the top of your carbs.  With a few screws and a spring removed, the carb slide will lift right out.  The needle is attached to your slide.  It's a little difficult, take pictures for reference, but it should be done at least once to make sure the needles are clean, and any crud is cleaned out.  Glad you got the pilot jets out easily...