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SU Choke sticking! Help

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mountainman

mountainman

Jedi Trainee
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The front carb choke will not return all the way home once it is pulled out. I have disconnected all the linkage and even lifted the piston to make sure it was not sticking on the needle. These carbs have been completely rebuilt but have sat for about 6 months. You can shove it home with a little pressure. Could it be the sealing gland washer or conical washer is to tight?
Thanks
Greg
 
Main thing is to remove the jet, and polish the outside surface until it is shiny. They used to be supplied that way, but many replacements are left dull, which both drags more on the seals and shortens their life.

I would also suggest replacing both the return spring outside, and the spring inside the jet that puts pressure on the seals. These aren't included in the rebuild kits, but are available separately from TRF (probably others as well). Some re-builders and/or DPOs cannot resist temptation, and stretch the inner spring in an attempt to stop the seals from leaking. That puts too much force on the seals, and causes the just to be too stiff. The return spring just gets tired, sometimes.

A very thin smear of silicone grease on the jet might help too, but of course don't let it block the holes.
 
:iagree:

I had the exact same problem with my TR4 carbs. Rebuilt, sat for a few months, front jet assembly sticks when I push the choke back in. I followed Randall's advice and disconnected the linkage and pulled the jet assembly all the way out. I spent some time polishing the jet assembly and put a thing layer of silicone grease on it. I found a little of silicone grease meant to lubricate brakes at the front counter of my local auto parts store, couldn't find any anywhere else.

Then I slid the jet back in, working it in and out feeling for any rough spots. Starts and runs like a champ now.
 
Dow Corning used to have "Stopcock Grease" for laboratory glass stoppers, now I think its renamed "111" silicone grease or the like.
 
some would argue that the nitrile o-ring seals prevent sticking better than the cork ones.

also - it seemed as if you were asking if this could be caused by over-tightening the large cork conical washer / big nut holding the jet assembly in place???? I would think that would NOT be a cause of the jet sticking.
 
I had the devil of a time with the rubber o-ring seals....ethanol fuels expanded the rubber causing substantial leaking...I'm sticking with 24 hour oil soaked cork seals
 
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