Stalling issue(under throttle)

[NA&CH]

Cleaned the front carb. Saw some markings. Any idea what they mean or are for. Also the piston pin with oil seams to be causing the piston to drag? Without the pin in the piston is free moving. With it installed it is tough to push up and it slides down... my gas gasket is broken and need a new one. Loss fuel in start up... Gas is also dripping from velocity stack just sitting. 

I turned the jet adjustment all the way lean when it was out. Righty tighty. 

Also should getting the float out be a royal PITA and me being afraid of breaking it?

Next rear carb cleaning. But I need a gasket to see if what I did was good. 

[NA&CH]

Front float bowl pics.

 

Chris

[Mark Maras]

 I've never worked on three screw SUs but I recall that the float cover must be rotated to remove it. If you're referring to the float pivot pin, it should just push out of the float cover bosses with finger pressure.

 Fuel running out of the stacks would indicate that a float is stuck, needle and seat are leaking or the float level is set too high.

  I think the markings on the butterfly are from ZTherapy. Premier SU rebuilders in Salem Or.

 Is the piston pin you referred to, the brass jet needle? If so the needle may be bent or the nozzle may need to be re-centered. Try screwing the mixture adjustment 2 1/2 turns down from the top and see if the piston is still dragging on something.

[NA&CH]

Thank you mark. I meant the oil dip stick. When that is in the piston is tough and not smooth. I order some gaskets and su oil for the proper parts. I thought the markings were Ztherapy. I have a call into them about their carbs. But if I have a set maybe just a rebuild. They are from 04 though. 

Chris

[Mark Maras]

The oil will give a lot of resistance which is normal when trying to raise the piston but it should rise (and fall) smoothly. 

[NA&CH]

The rear carb I push and it works freely. It also has the return spring. 

Front carb when I push the pin it is a struggle to push it and it "comes down" no clunk. A slight sound. 

I have ordered a new coil and electronic ignition. PerTronix system. The gaskets for float and Misc screws for the balance bar. Also a call into Ztherapy. 

Chris 

[Captain Obvious]

If everything is working properly, the pistons should be hard to lift with a finger, but should fall easily. So the one that lifts easy has a problem. Something is wrong with the check valve jiggly bits on the end of the screwed-in stalk.

Also, I'm not sure what you meant when you said that the rear carb has a return spring... If you are talking about the spring pushing the piston down, then they should BOTH have springs under the dome.

Other thoughts? I don't like the looks of at least one of your needles. It looks like it's installed too deep into the piston, and it also looks chewed up and worn some at the hilt where it has probably been rubbing against the nozzle. The nozzle looks to be worn oval as well due to that contact. Dome/Piston/Needle/Nozzle alignment is very important, and the three screw round tops can be a problem if someone has cut off or dug out the dome alignment nubs (as has been done to yours).

@Bruce Palmer Can describe the process necessary to align the domes (and hence the needles to the nozzles), but remember that each and every time you loosen or remove a dome, you must go through the same alignment procedure again.

Here's your pic with the needle that looks worn:

And here's your pic with what looks like a non-round nozzle hole that has been worn by contact with the needle:

[siteunseen]

I've realized after working on a few and participating in a bunch of "help me with my carbs" threads, one of the easiest and most notable problems is the position of the the float hanger and the metal tang that the needle rides on.  Mine was like yours, bent all to hell to get the valves opening and closing with the lids turned upside down.  That was the old way to set them when they had Grose Valves.  The newer style that has the small needle like pin will not hold the weight of the floats so you can not set them the way they show in the Z Therapy Just SUs DVD.  It took me a year to figure that out.

Your floats should look like this, the hanger should be parallel with the float's top and the tang should look like a bump not a ramp.  Your floats are closing the valve too soon causing low fuel in the float chamber.

Disregard the red circle

 

[siteunseen]

Here's good picture Zkars or Jarvo put up showing a way to measure the fuel level 23mm down from the underside of the lid.  It's the easiest way I found to get in the ballpark.

 

 Another thing I would suggest while you are getting the levels set is to stick the cork gaskets onto the lids with fuel proof black RTV.  A thin layer on the lids then lay the gaskets down and then lightly screw them back down to the float chambers while the RTV sets up.  You'll be able to remove them without damaging the cork gaskets.  Makes getting them back on a heck of a lot easier too. ?

 

Edited July 22, 2018 by siteunseen

[NA&CH]

Waiting on parts to fix some items. I have tried to call Ztherapy several times are they still doing carbs? I spoke with Bruce and he told me to call Steve and no answer? The number Bruce gave me just rings for a few minutes.  

I will see when I receive the gasket for the float and adjust the float if that works for me. 

I went by a Mechanics shop who works on antiques. A lot of euros and he was telling me to clean the needle with 1k sand paper clean it up a little? Anything on this? 

Thanks again,

Chris

[7tooZ]

Never heard of having to clean the needles


72 body with 71 interior, Eibach, Illumina, R180 CLSD, 83 close ratio, 3.90 gears, Zstory, SUs, BRE Libre wheels and front spoiler.

[Captain Obvious]

3 hours ago, NA&CH said:

I went by a Mechanics shop who works on antiques. A lot of euros and he was telling me to clean the needle with 1k sand paper clean it up a little? Anything on this?

Using sandpaper to remove even more material from needles that already have unintentional material removed from them probably isn't going to help.

To be honest, I'm a little lost on exactly what problem it is that your are chasing... Can you restate the problem you are trying to fix? Maybe a fresh start will help.