Carburetor question

[stou]

Maybe some of you noticed in my project writeup, http://www.fjowners.com/index.php?topic=19013.150

I have some problem with my engine tuning, probably related to the carbs. It run very well on idle and when I accelerate very slowly. But if I accelerate more normaly, the engine is missing a lot. This morning I looked at the spark plugs, and they look not too bad. A bit dark but I didn't rode a lot because of the engine missing on acceleration.



Since the problem is on throttle opening, it look more related to the main jet, needle and emulsion tube. When I rebuilded the carbs, I installed 112.5 main, with new emulsion tubes and the old needles. I think this is where the problem is. From Robert (RPM) comments on my writeup thread, the carbs I use is one from late 1100 & 1200. But I used the new emulsion tube that look from early 1100. I use the olds needles because the one in the kit for early 1100 are shorter. But I'm affraid the problem is comming from a bad match with olds needles and news emulsion tubes. What do you think?

The emulsion tubes look the same size but there's a kind of lips at the top on the old one that the new one doesn't have.



Here's a picture from my other thread, where we can see early 1100 parts on left and later 1100 & 1200 on right.

[RPM - Robert]

What is that hodge podge of stuff? Is that out of one set of carbs?

Slides are different. Shape and hole size.
Emulsion tubes obviously not the same.
The needle on the left is not a stock needle it is some sort of aftermarket needle.

Sounds like the pilot circuit is still dirty which is causing a stumble under acceleration. The other mess you got going is what parts are inside those things.

[Pat Conlon]

Have sync'ed the airflow?

[stou]

What is that hodge podge of stuff? Is that out of one set of carbs?

Slides are different. Shape and hole size.
Emulsion tubes obviously not the same.
The needle on the left is not a stock needle it is some sort of aftermarket needle.

Sounds like the pilot circuit is still dirty which is causing a stumble under acceleration. The other mess you got going is what parts are inside those things.

No Robert, it's from 2 sets of carbs and they was not cleaned when I took this picture. Now I have the carb set who is like the one on the right. But the carb kit I bought have needles and emulsion tubes like the left one. So I used the jets, emulsion tubes, o'ring and gasket I needed from the kit but used the old needles (right) because the one from the kit was shorter. The emulsion tubes from the kit are the same size but as you can see in the second picture, they doesn't have the higher part like the one on the right.

Have sync'ed the airflow?

I did the carbs sync (vaccum), is it what you mean by sync'ed airflow?

I wonder if the fuel mixture screw is ok. At some places on the net, I saw that it must be turned 2 1/2 turns and on other places I saw 3.  Can there's some fuel starving because the fuel mixture screw is not enough open?

[RPM - Robert]

The short needle from the kit goes with the flat emulsion tube and flat bottom slide. If not using that combination together it is wrong.

I don't know what that other needle is as it has a different taper profile. If you are not using the shrouded emulsion tubes with the curved bottom slides and the longer needles. You are using the wrong combination.

Regardless, it still sounds like carbs are dirty. By the symptoms you are describing. Look through almost every single carb problem on this forum 95% lead back to carbs (pilot circuit) being dirty still after they were cleaned.

[stou]

The short needle from the kit goes with the flat emulsion tube and flat bottom slide. If not using that combination together it is wrong.

That's also what I think. I have replaced the emulsion tubes with the cleaned olds one.

About the cleaning, I'll check another time to be sure everything is clean and every holes anss passages are free flowing.

[RPM - Robert]

There is also a passage in the float bowl that will effect it.

[stou]

I just came back for a very small test ride... with no licence plate    I just putted back the olds emulsion tubes and the bike is running very nicely.