Carburetor concoction...

[JRealHEMC]

I finally got around to cleaning my carbs after I removed them from my bike, and I see someone has blocked off one of the hoses with a screw...



Questions:
1. Why would someone do this?
2. Does anyone have a diagram or is there a thread on how to PROPERLY connect all of these lines?

Note: The bike ran like this... Not sure if this "fix" was to help something, or was used as a "work around" to another issue.
INSIGHT PLEASE...

[donebysunday]

block

May have been a block off when the PO got rid of the vacuum petcocks ?

[JRealHEMC]

May have been a block off when the PO got rid of the vacuum petcocks ?

What are the vacuum petcocks for, and why do people get rid of them??

[kboehringer]

What are the vacuum petcocks for, and why do people get rid of them??

JR,
Your bike is a Special, it didn't have vacuum petcocks. Your photo is a good bit fuzzy & dark but I suspect those hoses are from the OCTY that is SUPPOSED to be installed between Carb #1 & Carb #2. Did you have a little diaphragm gizmo there sitting on top of the carbs in that location?

There are about 1000 threads on the OCTY so I won't tell too much here. Basically, it is used to cut-off fuel when the bike is stopped. Some want them, others toss 'em. Not sure but don't THINK you can get the parts to rebuild them anymore. I have three XS11's. None have an OCTY.

Many (not all) people just eliminate the PRIME position on their petcocks (check for threads on this) and use only the ON position. Again, a zillion threads on this.

KURT

[JRealHEMC]

JR,
Your bike is a Special, it didn't have vacuum petcocks. Your photo is a good bit fuzzy & dark but I suspect those hoses are from the OCTY that is SUPPOSED to be installed between Carb #1 & Carb #2. Did you have a little diaphragm gizmo there sitting on top of the carbs in that location?

There are about 1000 threads on the OCTY so I won't tell too much here. Basically, it is used to cut-off fuel when the bike is stopped. Some want them, others toss 'em. Not sure but don't THINK you can get the parts to rebuild them anymore. I have three XS11's. None have an OCTY.

Many (not all) people just eliminate the PRIME position on their petcocks (check for threads on this) and use only the ON position. Again, a zillion threads on this.

KURT

Thanx, guess I'll get to thread searching.

[Prothec]

JR,
... Not sure but don't THINK you can get the parts to rebuild them anymore. ...

The K&L petcock rebuild kits that come with the vacuum diaphragm is used to rebuild the octy/fuel valve. The rebuilt kit costs around $35 though.

There are probably lots of new unused diaphragms from the kits laying around here.

[MPittma100]

Hoses

Those two hoses are likely the carb bowl vent hoses (hard to see in picture). They are normally hooked up to the factory air filter box. It appears that you are running pod filters and therefore have nothing to attach them to.

If the hoses are attached to the upper tees that are between both pairs of carbs, that is what they are. The bowl vents should not be plugged. Find you some small filters that can be installed in the end of the hoses to keep dirt out.

[JRealHEMC]

The line with the screw in it is coming from the 3rd port in this little dewhicky here...



By the way, can someone tell me what that is? I like to know these things...

[bikerphil]

That doohickey is the vacuum operated fuel shutoff valve, or 'octy'.

[JRealHEMC]

That doohickey is the vacuum operated fuel shutoff valve, or 'octy'.

Oooh, so that's the thingy they mentioned earlier in the thread. I'm gonna do some research, but so far I ASSUME if I disconnect that, and run the lines that come from between the carbs directly to my tank that it will complete the task of bypassing the "octy" or is it much more complicated than that?

[TopCatGr58]

Hey there,

Well, that last photo clearly shows the OCTY device...the vacuum controlled fuel valve. The nipple exposed on the right is for the vacuum hose to the #2 carb synch port...it provides the vacuum to actuate the valve when the engine is running, and when the engine stops, the loss of vacuum causes the valve to shut off the fuel to the carbs....for the just in case scenario that the carbs float valves may fail/leak and allow fuel to flood the carbs which then can flow into the cylinders, past the valves, the piston rings and contaminate the oil. IF this occurs undetected, you can burn up your engine/spin bearings, etc.!

The Petcocks IF OEM have 2 nipples. The front one is the PRIME and goes to the shorter hoses with the "T" fittings. The Long hose should have been connected to the rear nipple which flows in the ON position. SO...with that one plugged, the PO was using the PRIME function which was bypassing the OCTY to feed the carbs...so the OCTY probably wasn't working, especially IF it didn't have a vacuum hose on the side nipple!?

Some folks along with removing the OCTY will put inline manual shut off valves to provide the safety/security feature to protect against flooding when parked IF the petcocks, and the carbs float valves both fail/leak! Don't forget to also put INLINE fuel filters as well. And would suggest ALL NEW FUEL LINE also.

T.C.

[Schming]

The arrow is pointing to what we call the Octy, 'cause of all the hoses, which is a vacuum activated fuel valve that opens via a vacuum line connected to one of the carb manifold nipples. When the engine starts, actually as soon as the starter is turning the engine and the cylinder starts to pull vacuum the diaphragm in the octy lets fuel pass to feed the carbs.

It's actually a safety feature that shuts fuel flow from the tank as soon as the engine stops turning.

[JRealHEMC]

SO...with that one plugged, the PO was using the PRIME function which was bypassing the OCTY to feed the carbs...so the OCTY probably wasn't working, especially IF it didn't have a vacuum hose on the side nipple!?

Hey T.C.

Thanks, but the nipple on the side WAS connected to the carb. And why would they just block off ONE side when there are valves on both sides of the tank? (Which I also don't get the concept of having them on both sides.) Also, if I totally bypassed it, would I run the main lines to the "on" side of the petcock & do away with the "prime" side somehow, or the other way around? And is there a risk with doing that? I recall someone saying earlier in the thread that a lot of people do it with no problem. I basically just need "the right way to do it wrong" if that makes sense. Lol

[TopCatGr58]

The Nipple I'm talking about is just near the arrow in your photo, along the first curve...the exposed brass one. IF that was connected to the carb, it was wrong. The #2 carb's vac. nipple is only for the VAC. Adv. hose that runs down to the left side engine cover. That brass nipple should have been connected to the #2 or #3 INTAKE BOOT synch nipple! If it was connected to the petcock...definitely wrong.

The tank has a prominent groove down the middle, and so if you ran off just 1 side petcock, there's a chance you could miss some fuel when in a low/reserve fuel situation. Cap off the PRIME nipple, use the ON, reserve only flows out the ON nipple! IF capping it is too problematic, you can also "Y" connect them together before going to the filter/manual shut off inline valve, and finally to the carb bank OPPOSITE the petcock, allows less sharp bends in the fuel lines, and more slack when first lifting up the tank prior to disconnecting the lines.

T.C.

[JRealHEMC]

IF that was connected to the carb, it was wrong.

T.C.

Well by "connected to the carb" I guess I actually meant connected to the boot..



I really wanna just take the whole thing off, but from reading up on it, I'm a little scared... Does it really have to be manually shut off every time I stop, or is that just a precaution? I wish I could just leave it hooked up, but with the current set up I'm sure SOMETHING is wrong with it. I just want everything clean & organized. GRRR what do I do!? **pulls hair**