Petcock vs Carburetor vs Broken down on the side of the road

1977 Kawasaki KZ750 Twin B1:

Today I took the tank off and drained it.
I put two fuel lines on the petcock, turned the petcock to the ON position and let the fuel drain into a bucket.
As you know, each line directly feeds one of the two carbs.
While draining, I saw that fuel came out of only ONE of the two fuel line connections.
Then it would, then it wouldnt. Is this indicative of a blocked petcock?
Shouldnt fuel CONTINUALLY pour out of BOTH fuel lines to feed the carbs?  Photo below. 

Fuel came out of the spigot facing you only SOMETIMES.
The one pointing to the right had a continual flow of fuel coming out when the Petcock was in the ON position.

The tank or fuel valve has crud in it.
Remove bowl and blow through lines.
 

THANKS!!

wrote:

1977 Kawasaki KZ750 Twin B1:

Is this indicative of a blocked petcock?
Shouldnt fuel CONTINUALLY pour out of BOTH fuel lines to feed the carbs?  Photo below. 

Fuel came out of the spigot facing you only SOMETIMES.
The one pointing to the right had a continual flow of fuel coming out when the Petcock was in the ON position. 

Yes, fuel has to flow out of both fuel lines. A good clean will bring back the continual flow.

 
 

Thanks Sirocco.

So I took the petcock apart and dont see a filter. There was no filter in the bottom sediment cup AT ALL.
Sprayed carb cleaner in the portals and put it under runnng water. water flowed from both ports. It isnt blocked anymore. I also thoroughly cleaned the tank, washed the innards with soap and water (the tank has ZERO rust in it. The PO kept it well and its original, not coated), and quickly threw in some dry gas after blowing the tank out with a hairdryer (without the petcock on, then I put the petcock in and put drygas in it)

weird thing though. before i cleaned the petcock, when I had it in the reserve position. fuel would only come out of one portal. If I put it on ON, fuel came out of both. I mostly run my bike in the RESERVE position, but wont be doing that anymore. Can you explain why fuel would come out of only one tap in RESERVE but both on ON?

After i rebuild the carbs (they looked good but im changing everything anyway)  and put the bike back together, I will give you all an update. Thanks for your help!

wrote:

The tank or fuel valve has crud in it.
Remove bowl and blow through lines.

 

weird question. How does the tank pull from the tank when on reserve? I think I cleared the lines and blew into the long valve in the petcock. When in the reserve position no air flows through to the portals. But when on ON, it does. The shorter plastic looking valve next to the long one, seems to do nothing. How does a tank pull from the reserve then?

Is the valve assembled backwards?
Steve

wrote:

Is the valve assembled backwards?
Steve



 

I have no idea what you mean by that. The petcock worked fine for 4 years between me and the PO. Last winter I let the bike sit longer than usual and it started acting funny. There has been no change in the petcock configuration. Today I took off the petcock bowl, cleaned it, and blew carb cleaner in the ports. Nothing was changed from how its been for 4 years, during which time it worked fine.

I blew air through the main valve and it came out of the two ports, so those are clear. I have no idea how to test whether the reserve position is working because the tank is off the bike  and I wont be back "home" until after labor day. Im not going to fill it with fuel and let the tank sit, off the bike, for two weeks. My question is, how does the reserve fuel, when the petcock is on reserve, flow from the tank into the petcock, if not from the plastic tube right alongside the main metal valve that flows fuel when the petcock is in the ON position?

this isnt my petcock but a stock photo i found. Mine looks the same. What does the circled plastic thing do? Doesnt look like it can take in fuel. It has no holes.

 

The circled plastic thing is a filter for the RES inlet and the long tube for the ON inlet port of the petcock.

Thanks.

As I may have mentioned, i took the bowl off and noticed there is only a gasket, so the PO must have gotten rid of the main filter.
I took the petcock off again and put it in the RES position. then I blocked off port 1 and blew into port 2. air came ouf of the bowl portion. Did the reverse and got the same results so I think its clear now.