Fuel leak in new-to-me XS11S

[EKphys]

I am new to my XS11s. Great bike!

Yes, I checked the seals on both petcock valves last week. They were pretty worn. But I learned that if I pulled out the rubber washer I could flip it and the opposite side was in clean condition without wear. That seemed to stop my leak for a few days, but now its dripping again.

It seems to drip only from the left most carb (on the kick stand, of course the low side). Once more fuel than a carb-bowl has leaked, I figure it has to be coming directly form the tank as that much fuel shouldn't be in the carbs.

It actually filled up the air box with fuel the first time I found it. I just ordered a new petcock rubber seal on eBay and will try that next. There is no visible fuel until it comes out of the carbs, so I'm pretty convinced it is the valve passing fuel through and not leaking out of the valve at that point.

What advice/experience can folks lend about fuel leaks of this type?

Meanwhile, any good suggestions on the best replacement air filter? Mine is clearly fuel soaked...

EKPhys
1979 XS1100S

[XS1100_OEM4ME]

1st

1st, would need to know alot more, do you have the octy (check valve, looks like an otypuss) still in place. 2nd, did you turn off the petcocks after riding, next, if you had fuel in the airbox, you most likely have gas in your oil, you can change your oil or change your motor if you don't If you have the octy and it is working, your petcocks don't matter, you can't get gas past it when the motor is off. The seals on the petcocks, outside O rings, keep the gas from leaking down the tank, the other seals, send the fuel from res / run/ prim / off The octy only opens up the flow when the motor is running

I am new to my XS11s. Great bike!

Yes, I checked the seals on both petcock valves last week. They were pretty worn. But I learned that if I pulled out the rubber washer I could flip it and the opposite side was in clean condition without wear. That seemed to stop my leak for a few days, but now its dripping again.

It seems to drip only from the left most carb (on the kick stand, of course the low side). Once more fuel than a carb-bowl has leaked, I figure it has to be coming directly form the tank as that much fuel shouldn't be in the carbs.

It actually filled up the air box with fuel the first time I found it. I just ordered a new petcock rubber seal on eBay and will try that next. There is no visible fuel until it comes out of the carbs, so I'm pretty convinced it is the valve passing fuel through and not leaking out of the valve at that point.

What advice/experience can folks lend about fuel leaks of this type?

Meanwhile, any good suggestions on the best replacement air filter? Mine is clearly fuel soaked...

EKPhys
1979 XS1100S

[tinman905]

Sounds like your needle valves in your carb is not shutting off the fuel supply too. Even if you replace your petcock seals you will most likely find if you leave them on especially when your bike is on the side stand the fuel will still leak from your carb.
Check your oil as you may have a lot of fuel in your oil pan as well.
K&N filters are still available for a stock air box .

[natemoen]

First, as oem said, change your oil before you run the bike again. Doesn't take much gas to thin the oil enough so it can't do its job.

Second, as tinman said, you have at least 2 problem. If your petcocks were off then they leak and need to be fixed (I disagree with OEM here, it does matter if your petcocks leak no matter your setup. If they leak they need to be fixed.). Also your float needle valves in the carbs are leaking. Replacements can be bought for the valves. Last, if you have the octy (square little thing mounted on top of the carbs with a bunch of hoses) the it leaks as well, rebuild kits are available for this as well.

Also when were the carbs last cleaned?

[fredintoon]

I am new to my XS11s. Great bike! - - - It seems to drip only from the left most carb (on the kick stand, of course the low side). - - - Once more fuel than a carb-bowl has leaked, I figure it has to be coming directly form the tank as that much fuel shouldn't be in the carbs. - - - It actually filled up the air box with fuel the first time I found it. - - -

Hi Eric and welcome,
you have more than one problem.
1) Fuel don't shut off. Even if that gets fixed you still have problem 2), one or more of the carb needles is not sealing properly which allows the carb bowl(s) to overflow.
Which brings us to the biggie. 3) Some of the gas that overflowed into the airbox could have gotten into the engine oil.
Why is this a bad thing? If 2-stroke engines run on the 5% oil mixed with their gas why should gas in a 4-stroke's oil be a problem? Because 2-strokes have ball & roller bearings that can live with that. Running the XS11's plain bearings on gas-thinned oil will wreck them PDQ.
Note that XS11 rod end and main bearing shells are just about unfindable.
So first, change the oil. Then fix the carb needles & seats.
And now you can fix the gas taps.

[Danny Crawdad]

Check your other stuff first because it is MUCH more critical (gas in oil does not a fun time make), but after all that if you have still an actual external leak at the petcock, I would:

1) Replace he petcock o-rings. They are cheap and easily found, no reason to reuse the old one. Pull the petcocks and pull out the old rings, clean the mating surfaces well, and...

2) Put NEW fiber washers under the petcock mounting bolts.

3) Make sure those mounting bolts are FLAT BOTTOM! I had a constant leak on mine and it was because one of the flat bottom regular bolts had been replaced by a screw that had a sort of tapered/rounded bottom. This flexes the washer, and makes the gas go drippity. Even with a new o-ring and washers, the wrong bolt will pour gas. DAMHIK.

[GLoweVA]

Once you fix the leak(s), try some inline fuel filters (or at a minimum: make sure your petcock filter screens are good to go)
This will keep any 'debris' from fouling those carb float valves. Otherewise, you'd be right back to where this all started.

Just a thought:
If your petcocks/octy are good and are sealing off the gas like they should, there's still enough gas left in the lines that could drain down into the carbs (past the leaking carb float valve) to cause a little bit of overflow.

But if you airbox filled up, then you had some serious leakby. There should be a drain on the bottom of the airbox to let that kind of stuff out. Check your airbox and that way if it ever happens again, you won't fill your box up.

As for the air filter, I've got a K&N, so I'll never have to buy another one again. (sure it's a little more money, but in the long run the cost is worth it.)

Ditto on all what the others said about changing your oil.
Get some inexpensive no name brand stuff (for now) until you've got all your issues worked out. (save you a buck or two)
You could probably get away with reusing the filter, just make sure you drain all the bad oil out of it first.

PS. Welcome to the wonderful worrld of XS11s!!! This site is your one stop shop for all knowledge on these bikes. No matter what the issue, someone here has 'been there, done that' and can offer you some good advice.

It helps to put more info in your signature so the readers/responders know a little about you and your level of experience/knowledge.

[XS1100_OEM4ME]

+1

+1 on fixing the petcocks They will need to be fixed and not drip gas on all that hot stuff I just ment, "IF" the octy is there and working, the leaking petcocks will not get into the motor The kits are everywhere and cheap compaired to a new motor

First, as oem said, change your oil before you run the bike again. Doesn't take much gas to thin the oil enough so it can't do its job.

Second, as tinman said, you have at least 2 problem. If your petcocks were off then they leak and need to be fixed (I disagree with OEM here, it does matter if your petcocks leak no matter your setup. If they leak they need to be fixed.). Also your float needle valves in the carbs are leaking. Replacements can be bought for the valves. Last, if you have the octy (square little thing mounted on top of the carbs with a bunch of hoses) the it leaks as well, rebuild kits are available for this as well.

Also when were the carbs last cleaned?

[cywelchjr]

+1 on fixing the petcocks They will need to be fixed and not drip gas on all that hot stuff I just ment, "IF" the octy is there and working, the leaking petcocks will not get into the motor The kits are everywhere and cheap compaired to a new motor

Actually even with a working octy, if the petcocks are leaking the prime function can be leaking gas past the octy all the time, so the octy can be useless at what it does with leaky petcocks. So the reality is that all 3 valves need to work properly, at least in as much as the petcocks need to always send the fuel where to tell them to.

[XS1100_OEM4ME]

+1

+1 Cy, it would have to be shoot beyond belief, (with that kind of ware I would think gas would be pouring out the petcock) but it could happen I have the prim blocked off on my bike, so wasen't thinking about that YOU ARE THE MAN

Actually even with a working octy, if the petcocks are leaking the prime function can be leaking gas past the octy all the time, so the octy can be useless at what it does with leaky petcocks. So the reality is that all 3 valves need to work properly, at least in as much as the petcocks need to always send the fuel where to tell them to.

[EKphys]

Sounds like job 1 is the oil. Can do. I've run it very little since my leaking started. Recommends on a particular oil? I know for the next change it won't matter much...

I will pull the carbs and clean them up. Got back to it last night and drained all carbs. Pretty cruddy gas coming out. Not much history on the bike, so ill clean them out not knowing when they have been cleaned. Maybe a tank rinse is in order, too? Recommends on a source of replacement needles? Do I have cork floats on a 79?

I'm guessing its the original octy. Advice on inspecting this?

Thoughts on the carb boots? They are somewhat cracked, though don't visibly leak. Seems like a good time to replace them. Good sources? Rough cost?

Thanks all. What fun!

Eric

79 XS1100
20k miles when odo quit. Now...who knows!
I have shop and owners manuals... : }

[Danny Crawdad]

That's a big debate around here . I use Castrol 4T Motorcycle Oil, but your favorite 20w50 will more than likely work just fine. Some say avoid synthetic, some say it's fine. YMMV, IMHO, IANAL, etc .

Carb boots can be sourced cheaply from eBay but likely those cracks are just superficial and you can make it pretty again () with Plasti-dip, which is a liquid/spray rubber. It'll fill in the cracks.

[XS1100_OEM4ME]

Oil, many opinions, just make sure it doesn't have the friction modifiers that come in most car oil, they can make your clutch slip and need replaced. The boots sell for $60 to $100 on Ebay, but yours are probably OK inside When you clean the carbs, make sure you remove and clean the emulsion tubes well (missed one on my bike and had all kinds of fun finding what was wrong) If that much junk in carbs, i would flush the tank and lines to be sure you dont clogg the clean carbs. You can check the octy by sucking on the vac line (small one) and if fuel flows, then stops when not sucking, it is working, if not, just open up and clean, check diaphram. Your floats should be brass, can check for leaks buy holding under hot water in a bowl and looking for air bubbles, good luck

Sounds like job 1 is the oil. Can do. I've run it very little since my leaking started. Recommends on a particular oil? I know for the next change it won't matter much...

I will pull the carbs and clean them up. Got back to it last night and drained all carbs. Pretty cruddy gas coming out. Not much history on the bike, so ill clean them out not knowing when they have been cleaned. Maybe a tank rinse is in order, too? Recommends on a source of replacement needles? Do I have cork floats on a 79?

I'm guessing its the original octy. Advice on inspecting this?

Thoughts on the carb boots? They are somewhat cracked, though don't visibly leak. Seems like a good time to replace them. Good sources? Rough cost?

Thanks all. What fun!

Eric

79 XS1100
20k miles when odo quit. Now...who knows!
I have shop and owners manuals... : }

[EKphys]

Carbs...

So do I need to fully take apart the carbs and clean them out? Can I replace the needles and seats without a full tear down of the carbs if I find the petcock seal replacement doesnt stop my fuel leak?

Of course, I hope the petcock fix will stop the fuel, but...

I do need to pull the air box off and clean it out...

I picked up oil and will change that first.

[natemoen]

You can change the needles and seats withoit a full teardown but you are nearly 3/4 of the way to a full teardown at that point anyways, so why not. You say it is a new to you bike so who knows when the last time was that they were actually cleaned.