Carb Won't Fill

jkv357 · Post by **jkv357** » Mon Apr 17, 2017 9:58 am

Dr. Frankenstein wrote:But if you change the tab position, you change the float height, right...? I'm starting to lean more towards a bogus needle...

Right.

If the needle or the valve assembly is too long (incorrect part) it's going to make it close when the slightest upward pressure is applied by the float when the adjustment tab is in the proper position.

Dr. Frankenstein · Post by **Dr. Frankenstein** » Mon Apr 17, 2017 10:00 am

I will check that out and report back...seems very similar to the symptoms I'm having....

G-Man · Post by **G-Man** » Mon Apr 17, 2017 1:02 pm

John

Yes the Dream carb is similar to the pair on the CB72.

How about this.. attach the carb to a fuel supply and with the float bowl off, manual operate the float. Where does it cut off? Does it shut off at the level you measured the float height?

What kind of washer do you have under the needle valve body?

G

Dr. Frankenstein wrote:Hi G-Man - actually I only use non-ethanol gas for my bikes, unless I'm out somewhere and Absolutely have to get gas.

The gasket seems to be okay...it's not puffy or anything...and as far as the shape goes, I'll take a closer look and get back to you.

Is your CB72 carb typically found on the Dreams, or at least that set-up?

Dr. Frankenstein · Post by **Dr. Frankenstein** » Tue Apr 18, 2017 3:50 pm

Just got done comparing the two PW22 carbs I have - one is off of another CA77 I have that I want to get to - and I can find no differences between them.

I took them both apart, being careful not to mix up the parts, and measured each and every part with a micrometer, and they all measured the same, especially the pilot jet needles. Both needles appear to seat at the measured float height of 26.5mm, measured from the carb body, not the top of the little lip there .

I measured the pilot jets themselves, and both measured the same height with and without the little O-ring it sits on.

All the passages are clear and nothing APPEARS to be hanging up, but I still have fuel backing up into the line and not emptying into the bowl - on BOTH of them!

The only thing I can think of is the channel in the carb where the fuel goes in must have something to do with it, but I can spray carb cleaner down the passage underneath where it screws in to the carb body and watch it come out where it empties into the bowl - but put the bowls on and Nothing!

Since it is happening to BOTH carbs, I believe the problem is mechanical in nature, but I just can't figure out what. ???

Could it be the floats catching on the sides of the bowl when I put them back on? I checked the clearance, and both floats have a couple millimeters between them and the sides of the bowl...

The floats are not in upside down...

I am stumped...

Maybe measure the float height from the top of the little edge that runs around the carb body and NOT the carb body itself? I haven't tried that yet, I'm kind of thinking as I type this...but that would shorten the travel length of the floats and needle even more, I would think, by raising the float height 1 or 2 mm...

Again, I am stumped....ideas??

Dr. Frankenstein · Post by **Dr. Frankenstein** » Tue Apr 18, 2017 3:52 pm

Oh, G-Man - the little washer under the needle seat is the typical stiff, dark red one. I forgot to mention that to you in my post.

Dr. Frankenstein · Post by **Dr. Frankenstein** » Tue Apr 18, 2017 3:58 pm

...maybe adjust the tang Down more, so the needle has farther to fall, thereby opening up the fuel passage...?

But then I'd worry about the needle hanging up on the tang itself an not going back up into the seat when and if fuel started entering the bowl, and flooding the engine.

I don't know.

G-Man · Post by **G-Man** » Tue Apr 18, 2017 3:59 pm

How about some pictures? There are thousands of these that work OK.

Just to go right back to the beginning for a moment. When the float rises in the fuel in the bowl, it is suppsed to cut the fuel off. To get more fuel into the carb you have to consume some in the engine.

Are you sure that youre not worrying unnecesarily? Just a stupid question but something must be wrong here. Either the carb or your understanding of it.............

G

Dr. Frankenstein wrote:Oh, G-Man - the little washer under the needle seat is the typical stiff, dark red one. I forgot to mention that to you in my post.