Fuel leak from carb supply tube overflows only while running

Whats up guys. My first post here. I recently took all of my carbs apart because the orings on the tubes that connect e@ch carb were leaking. And while i was in there i decided to size my jets to 120. I bench synced the carbs and had the idle mixture screws set to 4 turns out and the bike was running like a champ. A ton more power throughout every gear. Everything was great for a few days, up until now. I fired it up and now i have a fuel leak coming from the overflow tubes for the fuel tubes that connect the carbs. There only 2 of these tubes. Theyre the long ones that are kept in place by a hold down right next to the clutch cable. Like i said, its only while the bike is running. And its leaking at a fast pace. Sorry forgot to mention 85 xj700 with air pods and 120 jets.

 

The fuel petcock is vacuum operated, fuel flows when the bike is running and stops when off. Your floats prob needs to be wet set, there are three sittings on petcock, reserve, on and prime, reserve and on is vacuum operated, prime is constantly on, I'm sure other people would have more info for you

 

how to wet set and check fuel levels

Setting the fuel levels

it could also be the neeedle valves are stuck or leaking and need to be replaced

 

Thanks for the info man. I recently rebuilt the fuel petcock and the fuel is only leaking while the bike is running, which points me away from those possibilities with the petcock and the floats. If it were the floats the fuel would be overflowing if the bike was on or off and the petecock doesnt seem to affect if its over flowing or not regardless of the position. Kinda scratchin my head on this one.

 

no with bike off no fuel flows through petcock unless it is on prime
set the petcock to prime and see if you have a leak
then
test your wet set fuel levels see if your fuel levels are properly set
could be your needles are sticking open
or your floats are binding on the posts
or needles binding on float tang

 

Great info on wet setting! I'll give that a try. Thanks alot!

 

With the engine off, petcock in the prime position its not leaking gas. I'll test the wet set fuel levels in the morning. Looks like I could have a whole lot of possibilities that are causing this. Thanks for the info XJ550H. Appreciate it.

 

Is this a stock or aftermarket petcock?

I know pretty much nothing about the XJ700 and the overflow tubes... however, is it possible that the tubes are hooked up incorrectly? Asking because if your wet set was off enough to cause a leak when running it should leak when on prime.

 

I would figure it would leak on prime to ? I just got a 85 xj700 and was wondering does your foot pegs have a little bit of play, do they move a little bit? Just wanted to know because mine do. It looks like it is meant to do that? Thanks

 

on 82 and 83 750 bikes the foot pegs are adjustable yours may be too

700n looks like only the passanger foot rests are adjustable

 

Well i figured out the problem. I put the fuel filter on backwards and all the sediment that got into the carbs wouldnt allow the float valves to seat fully. I cleaned out the fuel filter and the line goin to the carbs and filled and drained the bowls about 5 time to clear them. And i revved the motor up a lil bit to help this process along. Problem solved. Thanks for all your help guys. And my foot pegs were a lil wobbly, i was able to put larger washers over pegs so they get more support and now theyre pretty damn solid. Hope that helps.

 

good that it was a free fix

 

And by the way, i am completely puzzled why there wasnt fuel leaking from the over flows with the petcock in prime.

 

Perhaps something went wrong in your petcock rebuild. Check for fuel flow on prime. Might not be assembled properly.

 

Ive triple check that petcock. It operates correctly in all 3 positions. Im thinkin somehow the vacuum being applied to the carbs with that sediment against the valve seat with the bike running caused the leak from the overflow.

 

Stumplifter, The petcock is an original with a rebuild kit.