Gas leaking

So i just repaired my petcock on the '85 xj700x but its still leaking gas from the carbs overflow!

 

Probably the needles are not sealing....time to pull the carbs apart

 

Ya I hear ya, I think what you are getting at is the petcock should not let fuel flow when the engine is off. I did the same thing installed a new kit on my "X" and it would still flow a little gas. I would recommend getting another petcock that does not have the vacuum plate in it and only has the on/off/res. That is really the only way to go with these older petcock.

I am sure there will be others that say you can rebuild and shine up and hone the petcock, I am sure you can. I tried cleaning shining and that didn't work for me either.

Best of luck on what ever direction you go with the petcock. As for the needles not sealing this is true too, but why is gas getting to the carbs in the first place with the engine off?

 

Well I did rebuild but it didnt start leaking until I tried to start it. Didnt start so the battery might not be fully charged. Also carbs have been pulled and cleaned.

 

+1.
Not all of the petcocks can be rebuilt sucessfully.

Now if you have the petcock on prime to fill the carb bowls, and it's still overflowing (or the petcock set to ON, and overflowing while cranking the engine), then you do have faulty float needles or a stuck float.

The carbs have been cleaned how?

Did you break them apart, removing all of the seals, and replace them with new parts?
30 year-old carbs can't just be sprayed with carb cleaner.
Gotta do the whole job.
IN THE CHURCH OF CLEAN
Setting the fuel levels

 

The rack was taken apart and everything cleaned thoroughly, but nothing was replaced...

 

Always time to do it right the second time

 

On the petcock:
If gas is flowing when you're not running clearly to still have a petcock problem (petcock in ON position... not prime, not RES).

K-moe is right that some petcocks have aged/weathered beyond being able to be repaired. One last thing you might want to try is to take the petcock apart again and "peen" the metal disc on the diaphragm ever so slightly so it gets a tighter seat position. My petcock (after rebuild) was really trying my nerves. I was in and out of that darn thing at least 4 times... clean, polish, wipe, clean polish wipe... still drip, drip, drip... Then I peened it. No more drip!

On the carbs:
Did you do the work on the carbs yourself or did you have someone else do it? Are your needle valves the rubber tip kind or metal. If you have the rubber tip, and you didn't have any parts replaced, this might be your leak problem. Rubber tips will deteriorate over time. Due to this, they don't seat well.

 

If it only leaks when running, then either your float height is wrong, or your float valves are not sealing. Could be some small debris got in there and is holding them open. Do you have an inline filter on your fuel line? Is your gas tank completely clean of rust? If the answer to either of these is no, you should see about obtaining an inline filter, I have a cheap lawn mower filter from Advance Auto Parts in mine. I change it every other year or so. Over on the Vulcan 750 forums they have a trick they promote often of back blowing the carbs. It's not really advertised as a cure, more a stopgap troubleshooting step to see if you REALLY have to pull the carbs off (pulling carbs on a Vulcan 750 is a gigantic pain in the backside, ask me how I know).

The gist of it is, drain the float bowl, hook a hose up to the drain point, and blow back through with the fuel hose disconnected. If it's just a little piece of debris, this should at least temporarily knock it out so you can evaluate whether or not you have to pull the carbs to work on them. Of course, on the VN750s, they have individual fuel taps, and not a fuel rail, so it's more predictable where dislodged material will go (back into the tank, or out into the air if you have pulled the fuel hose).

If it leaks even when not running, then you have two problems, both the float valve and the petcock need some lovin'. With the bike off, at any given time one of those should suffice to stop fuel flow.