Leaky Carbs - looking for quick help

[vincejames]

Read through the carb guide already but looking for some additional opinions. I have a bunch of gas leaking into my uni pod filters. My float level is adjusted perfectly so I know that's not the issue. My seats are also clean. I'm thinking it's just these shotty vacuum petcocks even though I pulled them off, cleaned them up, and they seem to be working fine. Opinions?

 

[vincejames]

Yes. I know the petcock is turned a little.

 

[5twins]

You say you adjusted your floats but when you did so, did you measure both sides of each float? Many times, they are twisted or tweaked on the bracket and one float bulb sits higher or lower than the other. If that is the case and you only measure one side, the level you think you've got really isn't where it's at.

You may also have a worn out float needle and seat. Even if they're clean, they still won't seal properly if worn out. If they're borderline worn, a leaky petcock may push fuel past them. Have you checked your petcock and does it only flow fuel in the "Prime" position, no flow in the "On" or "Res" positions?

 

[vincejames]

It's actually floating in the on position too, which I know is incorrect. They are funky. Sometimes they flow in the on position sometimes they don't. Solution? Petcock rebuild kit maybe?

 

[vincejames]

Float level is exactly the same. Measured w/o gasket.

 

[vincejames]

I had a small leak from my right side petcock but I fixed that by disassembling the petcock and fixing the worn out gasket with RTV. I know this is a cheap route, but I didn't want to wait for new gaskets to get shipped.

 

[5twins]

Petcock rebuild kits may work, may not. It depends how worn the hard parts are. What you can check now and maybe remedy without a rebuild kit is the o-ring on the plunger that sticks in the back of the petcock. It's part of the diaphragm on the back. Sometimes you just need a new o-ring there. Sometimes you need to clean and polish the tapered seat the plunger fits into on the back of the petcock body. There's a good petcock rebuild thread on here somewhere. Maybe a search will turn it up for you.

I think your float needle and seat assemblies are on their way out. They may not be totally worn out yet, able to meter the fuel flow OK while the bike is running, but they don't seem to be able to hold back the force of a tank full of fuel pushing against them when the bike is shut off. They really weren't designed for that anyway. That's what the petcocks are for.

 

[vincejames]

Good stuff 5twins. I will let you know how this turns out. Thanks

 

[5twins]

If you decide to replace your float needles and seats, I recommend using originals. The aftermarket ones are hit and miss. Sometimes they work, sometimes not. Originals don't cost that much more anyway, only a couple dollars .....

http://www.boats.net/parts/detail/yamaha/Y-168-14190-20-00.html

My local dealer told me he won't use the aftermarket ones any more. Too many returns with leaks that he then had to fix for free.

 

[vincejames]

Good stuff. I've definitely had bad problems with crappy after market parts. Thanks!

 

[vincejames]

You were 100% correct. It was the seat and float needle. Interesting enough I have a friend who also had the same issue on 2 of his xs650s. He bought the set from MikesXS, they were garbage. We used the ones you suggested and fixed the issue. You the best 5twins!

 

[fredintoon]

Hi vince,
it's said you shouldn't trust the float needles & seats (even the good ones) to turn the gas off long term but should turn the gas taps to OFF when you park.
And the vacuum auto-OFF gas taps don't always work right neither.
What you can do with a vacuum tap is file the little nubbin off the gas tap's ON/OFF/PRIME plate and file the valve handle a bit shorter so it clears the underside of the gas tank so that the handle can be turned to point straight up.
This will give the tap a real actual genuine manual OFF position.

 

[5twins]

Actually, there is a way to convert the vac petcocks to manual ones, but it takes two because it involves swapping parts between them .....

http://en.650wiki.org/index.php/5.02.1_Vac_Petcock_Conversion

 

[fredintoon]

Hi 5twins,
yes, I saw that partswap trick some years back and did it on my XS11 Special when I installed an XS11 Standard tank on it.
My XS650 Special tank only has the one gas tap so the partswap trick can't work on it unless you find an opposite side gas tap to rob the part from.
The XS650 Standard tank I swapped onto my Special has the shorter gas tap slots that fit the manual gas taps so I didn't have vacuum taps to deal with.