gas leak from petcock!

[edavi394]

Hi, I just rebuilt my petcocks due to them leaking but they still run gas out when they are turned off. I too the tank back off the bike and in every position they leak. what can I do to fix this? buy new ones? it is really frustrating!

thanks

[Shawnb]

petcock

If you have decent ones buy gasket kit for valves clean them out like a carburater cleaning. tighten all your screw back down upon task completion and check. /should seal petcock, also inside diaphram should be replaced. should work.

[edavi394]

Hi, thanks. I did buy a kit and put it in. I cleaned it out good I thought but it might need to be a little better. I noticed on the diagram that when the gas is running out of the petcock it is running out of the vacuum side not the gas side.

[edavi394]

I put it back on and hooked the lines up and when it is switched to the on or res position it does not leak unless I have vacuum on it. how ever when I try to start it the gas just runs out of the carbs in a stream so I guess I have to rebuild the carbs after all.

unless someone knows something else to try

[edavi394]

should gass ever run from the vacuum side of the petcock? even if the tank is off the bike?

thanks

[mro]

standard petcock

Fuel should not be able to get to the vac side of petcock.
May have put it together wrong.

On another note, had read sometime ago that there was a petcock kit whose diaphram/plunger was short
Even so should not leak through vac line.


mro

[AlanB]

Hi Guys,

Fuel leaking from the vac side of a petcock is dumped into the carb boot and can fill a cylinder!.... From there it will either leak past the rings, dilute the oil and wreck the bearings, or lock the motor up when you attempt to start it; potentially bending rods......

Back in the '80s we used to see at least one Honda 900 or CBX every couple of months with a motor wrecked by fuel tap leaks......... probably the single biggest cause of terminal engine damage I have seen.

That is why I keep saying to CHUCK AWAY THE OCTY!! I converted my bike with non-vac taps years ago.

Second biggest would be low oil levels, third probably dirty oil....... All of the top three easily sorted!

AlanB

[egleaves]

That is why I keep saying to CHUCK AWAY THE OCTY!! I converted my bike with non-vac taps years ago.

I've had issues, off and on, with fuel leaking from my carbs and 99% of the time closing the petcocks solves the problem. However, sometimes I forget and once in a while I'll be greeted by a wall of gas fumes when I go out to the garage. I'm reading more things about the octy being unneccesary and possibly even a contributor to this problem, and now I'm debating whether or not to yank mine.

[egsols]

I had that debate......octy gone.

Benifits,

One less thing to go wrong.
Makes you use your petcocks so they don't sieze from non-use.
Makes your plumbing cleaner eliminating kinking and making tank removal/installation easier.
Allows you to add inline filters.

Need I say more?

[edavi394]

well I don't notice it leaking from the vac side when it is on the bike only notice it now when it is off the bike and you move the tank a little side to side it comes out for a little bit in a small stream ( like 1 or 2 seconds)

It was for some reason running gas out of the air box or carb on the number 4 side (I have the bottom of the air box off right now)

doesn't that mean the needle vaulve is stiking and the carbs need to be taken apart and cleaned?

I was really hoping to leave the octy on it but maybe I should take it off.

if I do then do you just hook a line to each side of the petcock then to each carb? so say on petcock 1 line 1 and 2 goes to carb 1 and 2?

thanks

[egsols]

Hi edavi394,

On my 79 special I ran a line from left prime to right prime (on the tank. I then ran a line with a filter from the left petcock to the the tee supplying 3 and 4. I ran the other line, with filter, from the right petcock to the tee supplying 1 and 2. Works out nice and clean.

If carbs are leaking then float is hanging up, stuck or valve is stuck or worn or dirty. Yes you will need to take them apart to make sure there is no dirt in the valve seat and inspect valve for wear and floats for hanging. Before you take it off you can always tap the side of the carbs with a screw driver handle and see if the leaking stops. If it stops that means that your float and/or valve is sticking. If it doesn't your float valve(s) are probably worn and not seating properly.

[edavi394]

ok thanks for the info. I think I will take the carbs off and rebuild them I have the kit anyway. I might try to bypass the octy and see where it gets me.