Flooding carbs - what's wrong?

[FormerGlory]

Bike ran perfectly...as did the petcocks...then I tore it down to rebuild. Octopus, fuel lines and carbs were removed, bagged and set aside over winter. They sat in my garage, but were bagged and kept clean.

Just installed the octopus, new fuel lines, carbs and connected everything. Verified the fuel hose to petcock connections with my shop manual. All good. Petcocks were on reserve, so I left them and added a gallon of new fuel.

Soon the bowls filled, overflowed and gas leaked from the filter pods. Stopped the flow by changing the petcocks to Off.

What's wrong? And can someone explain the petcock positions? What position for storage and what position for normal running?

Thanks

[jetmechmarty]

If you have routed all of your plumbing correctly, you should not experience fuel flow in the "RES" position.

"OFF" should allow no fuel to flow from either petcock spigot. You "should" be safe parked in that position.

"ON" and "RES" should allow fuel to flow from the "ON" spigot of the petcock to the vacuum shutoff valve. (octopus) Fuel should flow no further until the engine starts and vacuum opens the shutoff valve allowing fuel to flow to the carburetors.

"PRI" should allow fuel to flow directly from the "PRIME" spigot to the carburetors, bypassing the vacuum shutoff valve.

When fuel reaches your carburetors, the flow should stop once the bowl fills and the float valve closes. This is not happening for you. One or more of your float valves is not closing. You can tell which ones by which pods are getting wet.

Also, since your cock is positioned to "RES", your shutoff valve is not closed as it should be, or your plumbing is misrouted. You should be experiencing the same thing positioned to "ON". You should also experience flooding in "PRI".

[Rasputin]

In case you did not know as I did not for several years. The handle of the petcock points towards the position of the petcocks.
As you have recently re-installed these components there may be grunge in the parts even though you have said they were bagged etc.
Most likely that a sharp rap on the carb bowls would let everything sit right. I do that as a normal part of installing carbs just because.
If you have gas leaking into the carbs and out the air box or pods then there is no positive stop for fuel flow, which makes either the float level or the float needles suspect.

[FormerGlory]

Routing is correct, verified again. Check the floats and needles first and if nothing changes, rebuild the petcocks?

[Vinnie48]

In case you did not know as I did not for several years. The handle of the petcock points towards the position of the petcocks.
As you have recently re-installed these components there may be grunge in the parts even though you have said they were bagged etc.
Most likely that a sharp rap on the carb bowls would let everything sit right. I do that as a normal part of installing carbs just because.
If you have gas leaking into the carbs and out the air box or pods then there is no positive stop for fuel flow, which makes either the float level or the float needles suspect.

I have this issue too , and found out it leaks out only from carb #3 ...so tomorrow I'm gonna check that carb.

[TopCatGr58]

No, you need to fix the carbs, they should not leak no matter what position the petcocks are octy are doing. IF they are leaking they will flood and cause poor performance as well as a fire hazard. Once the carbs do not leak, then you can further test the petcocks and octy...or just throw the OCTY out as many have done...you have an OFF on the petcocks, just use it!

T.C.

[jetmechmarty]

Routing is correct, verified again. Check the floats and needles first and if nothing changes, rebuild the petcocks?

Your petcocks might be fine. If the engine is off and the carburetors are flooding in either the "ON" or "RES" position, (handle pointed down or up, vertical) your vacuum shutoff valve (octopus) has failed open. AND you have needles not sealing against their seats. You need to address both of these issues.

You can check your petcocks simply enough. Disconnect the fuel hose from them. Get something to catch the fuel. With the petcock in the "OFF" position, nothing flows. Go to "ON". Fuel should be pouring from one of the two spigots. Go to "RES". Fuel pours from the same spigot. Go to "PRI". Fuel pours from the other spigot. (I forgot which is which) If this is what you have, the petcock is fine.

Now you know which spigot is which. Check your plumbing from the "PRI" spigot. There should be a path for the fuel to reach the carburetors WITHOUT going through the shutoff valve. It passes through a "T". Check the plumbing from the "ON" spigot. There should be no way for the fuel to reach the carburetors without first passing through the shutoff valve.

If this is all correct, your shutoff valve has failed as have one or more of your float needles in the carburetors.

[Rasputin]

If you have gas leaking into the carbs and out the air box or pods then there is no positive stop for fuel flow, which makes either the float level or the float needles suspect.

Hey TC. in which part of this statement was I wrong?

[jetmechmarty]

Hey TC. in which part of this statement was I wrong?

I'm not T.C., but you aren't. "Wrong", that is.

[FormerGlory]

Thanks to all for the very informative education. As Marty described, I tested the petcocks...and both operate just as they should. The PRI spigot is the forwardmost spigot on both sides. My lines from these spigots connect to T's that bypass the shutoff valve in the octopus and feed the carbs directly.

I'll rap on the bowls, and then retest. We know the floats or needles are suspect. With the engine off, I'll first fill the bowls with the petcocks on PRI. If they overflow, the floats/needles will have to be checked. I'll then test on RES/ON to see if they continue to overflow. If they do, we know the shutoff valve is stuck open AND that the floats/needles aren't quite right.

Sound like a sound process?

Thanks

[jetmechmarty]

Sound like a sound process?

Yes. As others have pointed out, all you really need up top is a positive shutoff at the tank as you have verified. The float valves in the carburetors are a MUST FIX.

[TopCatGr58]

Hey TC. in which part of this statement was I wrong?

Hey Ras, I should have quoted HIS #4 post, that was the one I was replying to, just didn't want him going after the petcocks first when he should have been looking at the carbs float needles first, that's all!

T.C.