Carb Won't Fill

DJM · Post by **DJM** » Wed Apr 19, 2017 4:37 am

Obviously worth checking but in my case the filters certainly weren't blocked, newly built bike with everything ultrasonically cleaned. After yet another stoppage at the roadside when switching over to reserve, blowing in the tank did it immediately for me, I take care now never to let the fuel get too low.

Dr. Frankenstein · Post by **Dr. Frankenstein** » Wed Apr 19, 2017 5:13 am

Hi DJM - yes, that is weird, but absolutely what is going on with my bike; I'll try that next, because I have no explanation of what is happening...and it's nice to know I'm not the only one this has happened to! :) But very strange nonetheless...there has to be an explanation for it, but I have no idea what it is. I'll try blowing it into the tank next...

casamere - that's my problem - I'm not getting gas INTO the bowl from the gas tank.

seadog - I don't know about the gas cap; I believe I blew it out with my air hose, but at this point I'm checking everything.

jkv357 - RE: the "Fuel Valve or "needle and seat" nomenclature - you're absolutely right, I was just being fast and loose with terms..."the gas needle thingy" works too....;)

Dr. Frankenstein · Post by **Dr. Frankenstein** » Sun Apr 23, 2017 11:52 am

OK, more on the mysterious "won't fill" topic

I opened up the carbs to check on the float level - checked the arm that the floats are welded to because they looked like they were in more of a down-angle than they should be - I was able to adjust a little bit more until they looked like they were flat/straight like it shows in the manual.

Adjusted the floats to 26.5mm above the carb body, like it says in the manual - so I am right on spec for where the float height should be.

The problem is, as I put the bowl back on, I can SEE the floats bottom out on the bowl, then as the bowl closes with the carb body, I can SEE the floats go up because of the bowl itself being pushed up against the floats...and thereby closing the fuel valve!

So, if I am at spec on the float height, and the floats are NOT hanging up but instead being PUSHED up by the bowl itself to close the fuel valve, why is this happening?! Is the bowl wrong?? Is the tang adjusted too far down/up? The floats are not in upside down...

I don't get it...ideas??

DJM · Post by **DJM** » Sun Apr 23, 2017 12:00 pm

If you're certain that the floats are set correctly is it possible that you carbs have the wrong float bowls installed, are the CB72 and CB77 float bowls the same depth, I don't have any CB72 bowls here so can't check.

LM?

Dr. Frankenstein · Post by **Dr. Frankenstein** » Sun Apr 23, 2017 12:11 pm

I have no idea...I do have another CA77 carb I compared this one with, and they both look like the same floats/size/shape/diameter...the funny thing is, is I have the SAME problem with the other CA77 carb, too, which makes me wonder if the problem is with ME and not the carb...

But in either case, I am not getting the fuel to flow into the bowl.

I even tried blowing in the line with fuel in it just fro the hell of it to see if the fuel would flow in that way, but that didn't work either...at least I know the needle is doing it's job...

G-Man · Post by **G-Man** » Sun Apr 23, 2017 2:16 pm

We need some pictures. Could the float be in upside-down?

G

Dr. Frankenstein wrote:I have no idea...I do have another CA77 carb I compared this one with, and they both look like the same floats/size/shape/diameter...the funny thing is, is I have the SAME problem with the other CA77 carb, too, which makes me wonder if the problem is with ME and not the carb...

But in either case, I am not getting the fuel to flow into the bowl.

I even tried blowing in the line with fuel in it just fro the hell of it to see if the fuel would flow in that way, but that didn't work either...at least I know the needle is doing it's job...

Dr. Frankenstein · Post by **Dr. Frankenstein** » Sun Apr 23, 2017 2:25 pm

Actually, I'm conversing with Bill Silver as we speak - he indicated the tang on the floats is Way down from where it should be, and after installing a new right-out-of-the-pkg fuel valve and needle, (Keyster carb kit KH-1316) it would appear that I have had the entirely wrong needle in there.

I HAD the floats at 26.5 mm with the old setup - put in the New needle and valve, the floats came to 31mm...! So I may be on the track of something here...