'77 Petcock leak

My petcock started leaking horribly the other day from the little jettison in the plastic separator bit.

I opened it up and found a hole in one of the diaphragms. Sealed it up nice and well with gasket maker. Stretched the spring out a little. It's still leaking...

But I noticed that if I unplug the vacuum line it won't leak but it still runs??

There is gas in the oil so I need to change that before I ride again.

But is there any problem with just disconnecting the vacuum line and sealing it up as long as it works? I could just change the oil and make sure it stays free of gas. I was going to do a carb rebuild anyways.

Thanks!

Is it a 1977 Harley, Triumph, Honda, or what? :laugh: In other words please add the exact model of the bike to your signature line. Ed

We need some more info about your bike model and year.
Independent of your petcock problem your cabs have a needle valves that regulate the fuel flow
into the cabs and the fuel high in the float bowls.
Normally if the needle valves are do their job right no more fuel as necessary will flow into the carbs with an open petcock.
In your case they are let the fuel flow over the breathe cover into the engine oil.

Leaking gas 12" from your crotch is never a good thing. I'd get a new petcock.

I was never and will not be a friend of this vacuum petcocks, i would go the manual way.
To much trouble with so called "it makes your life easier thinks".
In the end they eaten your precious time and nerves.

Scirocco wrote: I was never and will not be a friend of this vacuum petcocks, i would go the manual way.
To much trouble with so called "it makes your life easier thinks".
In the end they eaten your precious time and nerves.

Well, the bike is a '77 so that's 40 years service life for the petcock.

He says the bike is a 1977, but is the petcock original? This is one reason I asked that he post the specific model. My bike is a 1977 KZ650 and it has a manual, not vacuum operated, petcock. I believe the 1977 KZ1000 models also had manual petcocks. So which 1977 KZ models came with vacuum operated petcocks as original equipment? Ed

I'm not sure which models had vacuum in 1977. Off hand I don't think any of the KZs had the vacuum petcock that year. They had vacuum petcocks earlier, the H2 750 used a vacuum petcock the whole model run from 1972-1975. I still say after 321,000 miles on KZs that I can remember, the vacuum beats the manual petcock by leaps and bounds.
Regarding the gas in oil, there is a ball check valve in the vacuum port in the petcock that ensures gas can't flow backwards into the carbs via the vacuum line should a diaphram fail, there are drain overflows on each carb that drain gas long before gas enters the oil should a needle/seat leak if the petcock does not shut off. To get gas in the oil= vacuum petcock fail "PLUS" needle/seat fail, "PLUS" overflow tubes fail.

Woops, sorry guys I figured you would know I was refering to a kz650 given the forum name. I found one of ed's old posts and I got a petcock rebuild kit. My gasket repair didn't hold up to gasoline so I think that was it cause the rebuild kit fixed it! Now time to replace the carb holders and rebuild and clean the carbs. Heerrreee we go... I've had this bike for over a year now. Strong beast it is. Keep this forum alive guys, really invaluable resource here.

And just because...

A really nice sharp 650, love the short 4 - 1, must be sounds like hell!