XJ11 Fuel flow curiosity

[KA1J]

I found the petcocks weren't working properly when I bought the bike in October when I found gas in the oil after leaving the bike sit in the on position for a week. I took it for a ride & when I stopped saw the puddle forming on the ground. I bought a pair of rebuild kits (not knowing I only needed one kit to do the job) and rebuilt the petcocks and replaced the diaphragm.

I removed the carbs today to start rebuilding them and found the oddest thing when I disconnected the fuel line from the Ts going into the carbs; In the off position, as expected the fuel does not flow from either fuel line going to the carbs.

When I turn the left petcock to on, fuel flows from the fuel line going to carbs 3&4 but not from the fuel line for 1&2.

If I turn the right petcock to on, fuel flows from the fuel line going to carbs 1&2 but not from the fuel line for 3&4.

This can't be right, the engine's not running so no fuel should flow in the on position. When I replaced the diaphragm I made sure the diaphragm moved when I sucked on the suction line I also took care to put the petcocks back together carefully and did one at a time and then checked that both mirrored each other in performance when blowing into each respective vent. I also did not unhook the hoses going to the octopus when I rebuilt this.

Idears?

Thanks

[Aches n Pains]

I assume you still have your "octy." In the "on" position, fuel should flow if there is vacuum on the line (ie; you are trying to start the bike). Only in the "prime" position will fuel flow with no vacuum.

Personally, I dislike that arrangement so I removed the octy. Also replaced the petcocks but that's another story.

If I have this wrong, please straighten me out.

Doug

[DGXSER]

I have a theory....

MY Theory is that the diaphram valve needs to see equal pressure on each side to operate properly. With only turning on one side at a time it may be "rocking" on its axis and opening to let fuel go by. Realize that once fuel goes into the Octy it can flow to either of the outlets. So it is only by nature that it is going to one side only. And perhaps the PO swapped which sides it goes to, since it seems odd that it would flow to opposite side.

Good thing is, your on the right track as to your puddles. The Octy or the Petcocks are not the root source of the issue, the float needle valves are. But your on your way to curing that.

[KA1J]

I assume you still have your "octy." In the "on" position, fuel should flow if there is vacuum on the line (ie; you are trying to start the bike). Only in the "prime" position will fuel flow with no vacuum.

Personally, I dislike that arrangement so I removed the octy. Also replaced the petcocks but that's another story.

If I have this wrong, please straighten me out.

Doug

Yes the Octy is in place as it was when I got the bike. (I had assumed there was a petcock like in the XJ650 where there is a diaphragm within the petcock. That's why I bought two petcock rebuild kits but only needed one...)

I like the way it works on the 650, you leave the petcock on 24/7/365 and fuel does not flow when the engine is off. Since that's the way it is supposed to work with the XJ11 and the Octy is what makes that happen, I left it on.

So with that: Prior to removing the carbs I had moved the petcocks both to the off position. and there were no surprises when I removed the carbs, the fuel in the tank did not flow from the gas lines to the carbs..

Now that the carbs were removed and I had a good view of the inside of the bike my curiosity got to me and I turned the LEFT petcock to ON expecting no fuel to flow from anywhere. Nothing flowed from the line to 1&2 but as I was watching the left fuel line for 1&2 cylinders I saw gas running over the engine but coming out of the fuel line for carbs 3&4. Turning the petcock back to OFF stopped the flow. I then turned the petcock 360 degrees and the only place the fuel stopped was in the off position.

So I tried the right petcock and the exact same results happened again except the leak was now coming from the gas line going to carbs 1&2 and nothing leaked from the 3&4 carb fuel lines.

Since that flow comes with no suction on the diaphragm unit and happens on the opposite side of the engine, I have to think something is awry but I don't have a clue as to that that is.

[KA1J]

MY Theory is that the diaphram valve needs to see equal pressure on each side to operate properly. With only turning on one side at a time it may be "rocking" on its axis and opening to let fuel go by. Realize that once fuel goes into the Octy it can flow to either of the outlets. So it is only by nature that it is going to one side only. And perhaps the PO swapped which sides it goes to, since it seems odd that it would flow to opposite side.

Good thing is, your on the right track as to your puddles. The Octy or the Petcocks are not the root source of the issue, the float needle valves are. But your on your way to curing that.

If someone with an Octy would be willing to go out & remove both of the fuel lines from their carbs and see if the fuel does not flow in the same pattern, that would tell me your hypothesis is right. Or if someone with an octy were 100% certain they had left their petcocks in the on position when removing the carbs and had no issues with leaking fuel, that would be the same.

Yes, the float valves have to be bad in one of the cylinders, I ordered valves and the replacement seats/O rings and gasket kit. I had so much crud in the XJ650 carbs, I expect the same in this one. In fact in the 650, one of the fuel jets in the #2 carb was unscrewed and I found it wedged under the float by the hinge. It might have been on the bottom of the bowl & wedged where it did when I turned the carbs over to remove the bowls. No telling what you'll find from a PO being creative.

[SFerinTEXAS]

As noted above you have 2 issues. As far as your original question goes it is obvious the fuel lines are not set up correctly. Better men than me could drop the fuel line image on this page but I will have to give you the link.

http://www.xs11.com/forum/showthread.php?t=713

Its a little hard to grasp but it works.Other variations can be used as well.

On my SF I use the octopus , petcock prime port blocked ,keeping the extra safety protection and either valve can feed all the carbs . That eliminates the tees(and prime). I run the rear fuel tank ports to the outer (in) octy ports. Then the inner (out) octy lines to filters and each carb set. If you ever need to prime it you will have to apply suction to the octy valve manually. Leave that to ones imagination.

[KA1J]

As noted above you have 2 issues. As far as your original question goes it is obvious the fuel lines are not set up correctly. Better men than me could drop the fuel line image on this page but I will have to give you the link.

http://www.xs11.com/forum/showthread.php?t=713

Its a little hard to grasp but it works.Other variations can be used as well.

Thanks for the link, I'd found that earlier today & here's a link that has a photo that has numbers written on hose lines & connections that spells it out well for dummies like me: http://www.xs11.com/forum/showthread...outing+diagram

I saved the jpg to the hard drive then expanded it and the numbers written on the hoses are much easier to see.

If the fuel lines are not correct, that was not my doing as I didn't disassemble the octopus and when I removed the petcocks I labeled each hose to put it back where it was attached. I didn't expect to hear mis-routing may be the cause of the fuel flow.

I have no way of knowing with the petcock/octopus arrangement, what to expect as a result when a petcock is set to different positions like ON & there is or there is not suction on the diaphragm. What is happening is not what I expected but these petcocks have two gas lines going to them and the XJ650 petcock has but one. In the XJ11 petcock there is no barrier to both gas lines at the same time.

Interesting to say the least.

[natemoen]

If its the same as the petcocks on the specials (if I understand correct they are) the front nipple is where gas will come out when set to prime and the rear nipple is where gas comes out when set to on or reserve.

[DGXSER]

There are several options for the issue the more I think about it, but all of them require looking over the piping arrangement and the petcocks.

First thing to check is that they are piped up as the diagram shows. Also, look at your petcocks. They will have an L or an R on them to indicate which side of the tank they go in (orientation is based on sitting on the bike in riding position for left and right.) If the PO swapped them side for side which can be done, then the outlets change for PRIME and ON/RESERVE.

As the diagram shows, the ON/RESERVE outlet should run to your OCT and if the petcocks are in the right spots will be the rear outlet of the petcocks. These lines should run to position 1 and 2 on the OCTY. Then 3 should run to carbs 1 & 2 with a T in that line, 4 runs to 3 & 4 carbs with a T in that line. The third T inlet comes from the other petcock outlet which is PRIME.

Sooo....If the PO messed up the piping, which could happen in several ways, it could cause the issue your seeing.

to test my original theory, someone with a known well functioning OCTY would need to turn only one petcock to the ON position with the lines to the carbs removed form the Ts at the carbs, Then if they get fuel running out of one side, it could confirm the thought. Alas, I have ditched that device on my bike.

[petejw]

have u had any thoughts on removing
the occy altogether?
just block off the front nipples on the petcocks
and use the back ones, thatll give u on and reserve.

but before doing that be sure to fix ur leaking carbs,
the last thing u need is fuel in the oil. jat.

[cywelchjr]

Another thing to consider is that many of the kits don't have a long enough plunger for the octy and it doesn't press into the valve area hard enough to seal. Most find that stretching the spring slightly makes it work. This also has been known to happen with standard petcocks which have the diaphragm in them as well, with the same fix.

[DGXSER]

Cy, I have heard of that on the Standard petcocks, in fact, the issue is that the plunger in the rebuild kit diaphragm assembly is actually a few mm shorter than the stock one. However, I did some very extensive measurements of the one for the Octy I got in my rebuild kits I bought from Georgefix on Ebay and they were spot on the same as the stock ones.

[KA1J]

I'll be back to the bike tomorrow & will look at the octy/fuel lines & be sure they are as the diagram shows. I'm 40 miles away from it right now. I wouldn't have thought they had been altered but it is more and more likely, I'm finding the PO has been active on this bike...

I do want to keep the octy as it's what does give me an off and I do like having the on, prime & reserve. I did though think twice about replacing the petcocks with an aftermarket only reserve, on & off petcock.

Oh yes, I made sure the R & L petcocks are on the correct sides.

This is quite an adventure!

[cywelchjr]

If the on taps of the petcocks are hooked to where the prime should go it would stay on without the engine running, but the prime would be off, but it's possible that it's not hooked up right. If the problem still exists with it hooked up correctly then something is wrong with the octy. If you were to remove it, no need to replace the petcocks since they have an off already, you would just cap the front taps on them and hook the rear taps to the carbs and they are manual petcocks without modification of the petcocks themselves like on other Yamaha models or standards.