Topic: weird carburetor behaviour

[mazingerzeca]

I wrote that they seemed to be clean before I cleaned them, but anyway I cleaned them, although they seemed to be clean BEFORE.

[lucky]

I have the carbs on the table, checking everything again.
About the air screw. I've installed it in the following order: screw, spring, metal washer, o-ring. But maybe that's the wrong order and I'm blocking the gas flowing with the o-ring and it should be screw, spring, o-ring, metal washer?

That is correct.
First into the hole is the O ring,then washer,spring, and brass pilot screw.
But did you look into the hole with a bright LED flashlight and make sure there is not an old O ring down in there or a piece of one?

[mazingerzeca]

"cleaned them" -- this could mean nothing, I can't analyze this method. 

What did you do to them?  exactly.  and how did you verify they were clean.

Disassembled them, put them in an ultrasonic cleaner with Simple Green, passed a guitar string through them, and after that I put them on the carburetor body, sprayed carb cleaner through the air hole and verified it passed through the jet. They can not be cleaner.

[Vinhead1957]

Or a clogged vent!

[mazingerzeca]

Back to my question. I lost the idle when I made two things:
- Changed the needle and jet, which should not affect, given that it works only at throtle openings.
- Set the float height to 14,5 (the height stated in the manual) instead of 16,5, which the carbs had.
The question is: does the float height (2 mm difference) affect the richness/leanness of the mixture?

[harisuluv]

Very early in this thread I said:

Very similar problem was posted a week ago.  Turns out the choke was not opening/closing fully cause it was binding.  After fixing the binding problem went away.

on your bike turning them in will lean the mixture yes.

I didn't see a response to this at all.  This is important also because you say it changes when the bike is warm.

[mazingerzeca]

The choke works perfectly. Checked.

[harisuluv]

I know it's annoying to ask for clarification, but you need to understand that simple things that are overlooked are often times real problems that don't get solved because someone "already did that."
 
So you took off the airbox and verified that they were operating correctly ON the bike NOT off the bike?  Fully opening and closing?

[mazingerzeca]

Another thing: took the plugs off. They were dark, not oily, dark due to rich mixture.

[mazingerzeca]

Another thing: took the plugs off. They were dark, not oily, dark due to rich mixture.

I know it's annoying to ask for clarification, but you need to understand that simple things that are overlooked are often times real problems that don't get solved because someone "already did that."
 
So you took off the airbox and verified that they were operating correctly ON the bike NOT off the bike?  Fully opening and closing?

Yes, I did, on the bike and with the cable, they open and close perfectly.

[harisuluv]

Would you mind posting pictures of the plugs?

What mixture screw settings have you tried other than the one you mentioned in your specs?

[lucky]

Back to my question. I lost the idle when I made two things:
- Changed the needle and jet, which should not affect, given that it works only at throtle openings.
- Set the float height to 14,5 (the height stated in the manual) instead of 16,5, which the carbs had.
The question is: does the float height (2 mm difference) affect the richness/leanness of the mixture?

The float height usually does not effect the richness or leaness, but if the float bowl runs out of fuel the engine will lean out.

[mazingerzeca]

Finally, I went back to the first or second step, and changed the new needles and jets for the old ones that I had, which were worn, and the bike runs at idle! I didn't synchronized them, I just wanted to post it. Did some research and found out that the problem could be in the needles I used, which came on the Keyster rebuild kit that I used, so the problem should be there.

[harisuluv]

Well that's good.  It's always preferable to use the OEM brass parts, especially the needles. 

[bjbuchanan]

I bet that the stiffer springs that are supposedly in the keysters, combined with the lower float height made the pilot starve

[flybox1]

I've never seen actual comparison numbers, but it has been discussed that needle taper, and actual jet dimentions are different from OEM...which have caused more than a few headaches.  Glad you found a piece of the puzzle.

Felt bad for Atletico today.  They played a great 85 minutes.