Petcock vacuum question

[Bartman]

I have been using no vacuum on my (unknown) petcocks for a year by just turning to prime when starting and off when stopping.
I decided to clean and use the correct petcocks from my backup tank and wondered exactly which location the vacuum hoses are to be connected to? Does the left side go to the sync tube on no. 1 and the right one go to no. 4?
Or are they connected and go to a single point, and if so which location?

Thanks

Bartman

[natemoen]

You can do either. Most do right side to the #3 and left side to #2. You could though T the hosts together and connect both to a single sync port.

[rdmcguy]

petcocks?

Without knowing what tank special or standard makes it difficult to assist you
As you do not mention the octy,i will guess standard,
the vacuum lines go to the 'PETCOCKS not the carbs.
one line from intake manifold to petcock on one side of bike
one line from intake manifold on opposite side to other petcock
Also vacuum line from left engine side ...Shifter side ,,,
goes to # 2 carb body

[jetmechmarty]

The profile says standard.

Bartman, your bike shares petcocks with the XS650 if you get desperate. Also, I'm right up the road, neighbor!

[Ken Talbot]

The profile may standard, but he talks about using "OFF" position, which indicates petcocks from a Special. If that is the case, there is a much more complex routing involving the vacuum controlled octopus. Need to sort out first just exactly what you have. Pictures would help a lot!

[Bartman]

Standard tank,
Hey Marty, I need to come meet you soon.



The left petcocks have been on my bike this last year.

If I totally rebuild them will they leak or do I need to go to pingels?

I don't have filters for the right petcocks that I believe are the correct ones for the 79 standard tank.

[motoman]

Standard tank,
Hey Marty, I need to come meet you soon.



The left petcocks have been on my bike this last year.

If I totally rebuild them will they leak or do I need to go to pingels?

I don't have filters for the right petcocks that I believe are the correct ones for the 79 standard tank.

Right side ones are for the Standard tank.

[jetmechmarty]

Copy these instructions from XJBikes.com and they will work after you rebuild them.
Rebuilding the Yamaha Vacuum Fuel Valve w/pics

The plastic towers are still available from the mothership. 1J7-24514-02-00 NET,FILTER 1

[MPittma100]

Petcock

I have been using no vacuum on my (unknown) petcocks for a year by just turning to prime when starting and off when stopping.
I decided to clean and use the correct petcocks from my backup tank and wondered exactly which location the vacuum hoses are to be connected to? Does the left side go to the sync tube on no. 1 and the right one go to no. 4?
Or are they connected and go to a single point, and if so which location?

Thanks

Bartman

Nothing wrong that I can think of by not using the vacuum function of your petcock. With the shut engine off you think you are actually shutting the fuel off. With this style petcock we are lead to believe that if there is no vaccuum - there is no fuel. This is often not true. Vacuum petcocks can and do leak fuel without vacuum applied. I just rebuilt two for this reason.

If you have a leaky carburetor or two, and a leaky petcock or two, there is a real good chance that you will end up with a couple of extra quarts of gasoline mixed with the engine oil. NOT GOOD!

My vote is to somehow modify the vacuum petcocks to be able to absolutely shut the fuel off manually. If not, there is a need to check them periodically to ensure that they are not leaking when the engine is shut off (no vacuum). When installing rebuild kits in the vacuum petcocks, you still have to verify that the diaphragm oring is stopping the fuel flow. Sometimes the oring seat is compromised by corrossion or some other foreign object that will prevent it from stopping fuel flow.

One tank that I have had some Pingle brand petcocks installed by PO. I really like them. OFF-ON-RESERVE.

[Schming]

Manual shutoff

You can install inline manual shutoffs after the petcocks as a failsafe

[bikerphil]

I use an inline Pingle vacuum shutoff valve, very reliable.

[fredintoon]

I have been using no vacuum on my (unknown) petcocks for a year by just turning to prime when starting and off when stopping.
I decided to clean and use the correct petcocks from my backup tank and wondered exactly which location the vacuum hoses are to be connected to? Does the left side go to the sync tube on no. 1 and the right one go to no. 4?
Or are they connected and go to a single point, and if so which location?

Thanks

Bartman

Hi Bartman,
you don't need no steenkin' vacuum tubes, cap 'em off at the manifold connectors.
Clean the taps up good like the link sez.
Swap the leftside and rightside tap inners into the opposite tap bodies.
Now, ON will be OFF, RES will be ON and PRI will be RES.
Just gotta remember to turn the gas off when you park, just like grandpa on his Norton.

[TopCatGr58]

Hey Bartman,

I've corrected your previous posts....they are called petcocks.....not multicolored birds with big tail feathers!

That left one doesn't look like an XS11 petcock, the outlet spigot is on an angle vs. the 2 on the right that have already been identified as XS standard units.

Hey Phil, at least your vacuum pingle only has 2 fuel spigots, not 8, but it's still another vac. controlled device....vs. a truly manual on/off valve. Granted even a manual valve can fail when the internal rubber parts degrade. So....unless someone is actually taking the lines off and periodically testing their functionality, then nothing is truly foolproof, but I still like the idea of a manual on/off inline valve vs. a vacuum controlled one. I don't think the manual one would need to be turned off at every stop, just when parking for an extended time period....ie. overnight or such.

T.C.

[Bartman]

Thanks for the comments,

and for fixing my poor spelling: PETCOCKS...

Marty, that was a great how to clean post. I need to go back and do mine right now!

I tested the carbs over night to see if they leaked back last year, but couldn't get the petcocks to not drip, so I have been just turning them off after each ride.

I had a problem several weeks ago when I noticed that the bike was getting harder to crank. When warmed up, it would start with no problem, but after sitting for several days it was very hard. During this time, I took the seat to be recovered and the bike sat for a full week without riding. When I put the seat back on there was gas everywhere. I had filled the tank up with non-alcohol gas the week before and all of that pressure had pushed both a turned off petcock and needle/seat to leak.

I ordered a 12v fuel cut off and put it in line, but I think that it starved the carbs and I almost didn't make it back home. Either I need to put larger pipes on it or get the pingle as Phil mentioned.

I am so cheap, either I need to spend $70 for 2 rebuild kits, or pingles, or?

Do you use one or two of those pingle's??

[bikerphil]

I use one Pingle vac shutoff valve and I am running one petcock T'd into the two carb fuel inlets and an inline filter. You really need to get your carbs to stop leaking, I'd replace the float needles with new ones and the seats can be polished with a Q-tip and chrome polish. Also make sure the small ring gaskets where the seats thread in are good. Buying 4 carb kits are the expensive way to go, a package of float needles is @ $20, BTW the Pingle vac. valve is @ $100.