Topic: *&$&^#$ Petcock! aka my petcock woes

[ajinreno]

I have a 76 550k with a custom tank. The petcock it has is the type with two fasteners inside the petcock bowl.
It was leaking like crazy, enough to drain the tank in about 24 hours.

I bought a new one.

Put it on and had no problems at first, but while dealing with other problems, I discovered that it was not shutting off.

As pointed out in another thread, I was missing fiber washers on the fasteners that hold it to the tank inside the bowl of the petcock. I had some neoprene washers so cut them down to size and put them on.

At first it seemed to work, but then within a day it still wouldn't shut off and within another day the new petcock is now leaking as bad as my first one! (enough to drain the tank in 24 hours.)

At closer look....the fuel is continuously running so it is backing up in the fuel lines and seeping out the top of the fuel line where it connects with the petcock. Why would it do that? If I leave the gas on on my other bike, it doesn't back up and seep out the top! Should I have clamps around the fuel line at the petcock?

[mystic_1]

The stock fuel lines were metric, and didn't need a clamp apparently.  Most people, when changint the lines, wind up with 1/4 inch hose which is slightly too big, so you need clamps with those.

That said, if the petcock is shut off, no fuel should be flowing into the lines at all.  Did you check to see if the neoprene washers have gone south on you?  The fact that your fix worked for a little while suggests that this is where the problem lies.

mystic_1

[greenjeans]

Any idea where to find metric fuel line ?   That sure would be easier than wrestling with tiny hose clamps in tiny spaces with my big meat paws....

[TwoTired]

Any idea where to find metric fuel line ?   That sure would be easier than wrestling with tiny hose clamps in tiny spaces with my big meat paws....

Places that sell parts for metric bikes.  Honda dealer, etc.

http://forums.sohc4.net/index.php?topic=28636.msg294227#msg294227

http://forums.sohc4.net/index.php?topic=28636.msg294239#msg294239

[kghost]

Come on gents...

Washers or not...fuel flows from the bowl...thru the petcock..down the fuel lines or line.

I have had a very similiar problem many times.

Heres what the culprit has been in my case's.

1. Corrosion of the mating surfaces in the petcock. Sometimes the lever arm itself has been pitted severely. Enough to allow fuel to seep past.

Sometimes the surface inside the petcock body itself has been corroded...same result. Large pits and then the rubber washer doesn't seal.

2. Damaged holes in the body. Sometimes they are corrosion damaged causing the small lip to chip off.

Below is some of the corrosion damage I'm talking about....

Note the corrosion damage to the lever.


Note the corrosion damage to the bowl mating surface..

[bryanj]

Neoprene washers wont work you need the proper thick, odd sized, fibre ones or the "dowty" type i described in a previous post. New tap and proper fittment=no leak through

[ajinreno]

Thanks again gents...lesson learned...neoprene washers no good. Fiber washers good. I can actually shut my gas off now. And some zip ties around my fuel lines seems to have cured the leaking.