Fuel Leak - what am I missing - done it all(?)

[psifactor99]

Hey guys - awesome site - lots-o-experts - new to forum but not XS11,

Had my stock 79 XS11 since 80 and read all the posts concerning fuel leaking into air box.

So, I had carbs professionally rebuilt last month by a guy that has done many and has excellent feedback - everything in the carbs, even oriface brass replaced, floats, needles, diaphrams. Both petcocks rubber seals are all new and metal gently (dremel) wire-wheel cleaned, leak checked and no leakage out of petcocks when tank is removed from bike. And, I always shut off petcocks after riding. The fuel hose spyder is original. The hoses are in great condition (pliable - no cracks) as bike has always been garaged

Dang-it, a very small spot of fuel shows up underneath the bike and air box has a bit of fuel in it. Bike ran great when I first put rebuilt carbs on and ran it. Then, it sat for a couple of weeks due to hot weather.

What am I missing?

Mark

[bikerphil]

Sometimes the replacement bowl gaskets run a bit large on the inside and can cause a float to hang up. They can be trimmed down some. Don't know if this is your problem for sure, but it could be.

[motoman]

Missing?.......riding in the hotweather. Before riding, check make sure fuel didn't get in crankcase oil....not good. Ride it some, maybe just had a float hung up a bit.

[planedick]

Model

You didn't say if it was a standard or special and no indication in your signiture. The special would have this problem if the diaphram in the spider is broken. I thought maybe it was a special because you said you turned off the fuel when you stopped. The Standard model has no off position.

[DGXSER]

Also mentioend the spyder better known here as the Octy. This leads down the "special" path.

If those carbs were just rebuilt with new float valves and seats, then the petcocks or the Octy should not cause a leak. They should seal against tank pressure running or not. I would tend to agree with Phil on the gasket, or you just got a bit of sludge from the stirred up tank into the carbs and it could pass through the carb.

[Incubus]

Fuel in the airbox comes from the carbs overflowing. Carbs overflowing comes from one or more carb needle valves not sealing correctly. Aftermarket carb bowl gaskets can have a slight lip inside the bowls that the floats can catch on.
If it were my bike I would look there first.

Patrick

[psifactor99]

Discovered the cause of the leak...holes in a float

Thanks for the reminder that fuel overflowing one or more bowls can cause
the back flooding into the airbox. That was the problem area.

What I found was that the #2 carb float had three pinhole leaks on one side of the float pair. I discovered that as I was inspecting the needle valves and seats. I heard sloshing around (and my hearing is not that good) when I removed the floats. Then, used a magnifying glass to ID the very small holes in the brass float.

Now, I discover the brass floats are selling for $100 each (eBay) - ouch!
I am hoping that there is a replacement that does not use the brass float (2A2-14985-00-00) but an upgrade to rubber or some other material. Still looking...

Anyone know if there is a cheaper-better conversion?

Follow-up #1: Found that NW Vintage Cycle has them for $46.49 each - better...

[DGXSER]

Wow...Folks on ebay really ARE gullible I guess. The XS11 and the XS650 share these parts. Here is a link to ones that should work for you, you can get the plastic ones that came in the later models if desired.

If you have brass floats you probably also have the metal tipped needle valves. There is another "upgrade" to buy the float valve and seat for an XV920 (Virago 920) that will thread into the carb body the same os the ones you have and use the viton tipped valves that lost longer and seal better.

[psifactor99]

Parts is parts

Ebay was just my first stop Super Guru, so gullible, I don't think so - I've owned my 1100 since 1980 and can shop for parts and discovered Mike's site in a couple of minutes when the shopping became sport.

But, thanks for the helpful info on the cross reference to the plastic floats and better seats...

[radical123]

parts

ok i got to know dgxster will the Carb Float Valve (Needle & Seat) on that same page at xsmikes work with our carbs? 80 up and 79 down.
thanks

[DGXSER]

Sorry PSIFactor, I did not mean you as gullible, I meant whoever was buying the floats at $100 a peice on ebay. It is sometimes so hard to figure intent over the internet, typically I am not the kind to call folks names or be rude, at least until I get to know you alittle. Then it is only in fun, typically.

I am not certain on the threaded in type as I have never owned the 78-79 carbs, but the BS34 push in type with the o-ring seal are a match.

I know the plastic floats will work, as I know a local member who has them in his 79. The only thing that throws a curve on the seats they list for the early models is it shows them as BS38 carbs and ours are BS34.

Every set I have worked on either the jets got obliterated getting them out or the PO had "tuned" the carbs with some really crazy jetting, so I have just bought the kits form Georgefix on ebay that come with all the jets and the float needle valves and seats along with new mixture screws with the springs, seals, and washers.

[dbeardslee]

The brass floats that mikes sells definitely won't fit our bikes - they're way too wide - DAMHIK . On the 78/79 carbs you need the screw in type of fuel valves. The ones at mikes 48-5019 and 48-1429 look like the right parts, but the part numbers don't match up on the yamaha fiche. If you're going to install the plastic floats, might I suggest XV920 fuel valves? They use the viton tipped needles, which seal better and last longer, and they match up very well with the plastic floats. On mine I barely had to bend the tabs at all to get them at 25.5 mm. You can get them at Z1 Enterprises.

[TopCatGr58]

Hey Radical,

The 80 and up carbs that use the pressed in seat and viton tipped valves can use the ones on MikesXS. But the early model carbs that want to go to the newer viton needles have to get the XV920 seats and valves as stated above. If you want to use the older metal needles, then Mikes will work, but again, the seats are different as best I can remember. They(mikes) offers 2 sizes of the screw in seats, but I think I remember other folks trying them out, and they will not work on our carbs. And the official Yamaha parts numbers are quite different for those 2 types on mikes vs. the early xs11's.

T.C.

[dbeardslee]

the early model carbs that want to go to the newer viton needles have to get the XV920 seats and valves

When I first installed viton tipped needles I used the old seats. Measured against the XV920 seats, the hole in the stockers is only .001" smaller. They worked, but the problem is the viton tipped needles sit lower in the stock seats, and it requires you to bend the float tabs so far that they have to be rounded off to keep from catching on the edge of the seat. I just didn't like having that much angle on the tabs, so I installed the XV920 seats, and with them the tabs are nearly straight. Rather than a fiber washer, the XV920 valves use one made out of aluminum, and it's a bit thicker than the fiber. I'm thinkin' that may be what raises them up enough for the tabs not to be a problem. Might be able to accomplish the same thing with the appropriate washer under the stockers, but for what fuel valves cost it's probably easier just to replace them. I like the screen arrangement better on the XV920's too.

[zejaybee]

Another source for brass floats...

Here is a great source for the brass floats if you want them...
http://www.boats.net/parts/detail/ya...985-01-00.html

Just rebuilt my carbs and replaced all the floats due to the stock ones being somewhat crushed by compressed air cleaning. Never again will I let someone else clean my carbs. )