fuel leak is killing me!! HELP!!

[freak_leg]

So I've been dealing with a fuel leak since i tryed to get rolling this spring.
Its actually 2 leaks. 1 is coming from the fuel T between carbs 3 and 4 the 30year old rubber had enought. so cheap fix on that I cut the rubber off the metal inside and put some O rings on to seal. Its working for the most part. I need some fatter rings so that it seals tighter. Leak number 2 and the one that is making me want to tear my hair our is coming from the right petcock. It was leaking from the buttom gasket on the petcock assembly. So i took it off to inspect. Turns out I'm missing one of the 4 screws and the rest of the screws were finger tight. so I took the assembly apart. I've been in here before so i knew what i was looking at. the gaskets and the rubber diaphram looked good so I put it all back togeather. To test I hooked up the fuel lines, pluged the end of the line put some gas in the tank and waited for a leak. That was 2 days ago and it wouldnt start leaking. So I put my inline filters back on and connected to the carbs. 30 seconds later the petcock is leaking as bad as ever I need some help here. could the one missing screw (one of the dished head screws next to the fuel line) cause the leak once the fuel line is putting pressure on the assembly? If so does anyone have a spare they could send my way?? Also what I found funny, when the valve is set to "PRI" the fuel flows freely from the line, but on "RES" or "ON" very little if anything flows. Did I put the diaphram in wrong? I put it back the way it was, but that isnt saying its not wrong. This poor old girl has been molested by countless shade tree guys. I'm Trying to bring her back to some glory. Part by part its getting close.

Some one please help. Am I missing something here??

[Incubus]

Yes, you need all the parts to put your petcocks back together. If they only needed three screws then Yamaha never would have spent the money on the fourth.

Second, your petcocks are working properly if there is no or very little flow at the ON position. They are vacuum operated. Suck on the vacuum line that runs to the carb boot and fuel should flow freely. If it does not, then you have a problem.

BTW, stock Standard petcocks are the Devil's work and you will require chants, magic and an inhuman amount of luck to make them work correctly.

Patrick

[fabricgator]

Special screw or washer....

I'm just shooting fish here, but are the other mounting screws or washers... are they something special?

I seem to remember either a rubberized or gasket material washer OR a special screw with a machined place for an o ring.

I think the screw holes into the tank are open to the fuel and require a sealing mechanism if I remember correctly.

[freak_leg]

to clarify are some pics of the screw... or lack there of
[IMG][/IMG]
[IMG][/IMG]
I need another one of these screws

[bikerphil]

Bring the screw to Ace Hardware/Motorcycle Parts and they should be able to match somthing up for you.