Topic: Reproduction Fuel Petcocks - Still Letting Fuel by When in the Off Position

[whitjonw]

Hi All,

I have purchased a couple of aftermarket, reproduction petcocks for my 1973 CB500 and 1974 CB750 and find that they both leak/let fuel past the valve when the fuel valve is in the off position. Is this a common occurrence/find with these reproduction petcocks ? They look exactly like the Honda OEM petcocks.

Is there a fix for this ?


- Edited to clarify

[TwoTired]

Do you have the proper soft washers for the mounting screws?

[ekpent]

 Like TT mentioned at least on the 750 there are two special washer gaskets,may be fiber, that go on the bolts that mount it to the tank inside the petcock. The stock ones are kind of a reddish color.

[whitjonw]

Yes, I do have the washers and they are correctly installed. The problem is that the  fuel drains past the valve into the float bowls....where it is supposed to go. Only, when the fuel valve is in the off position, there shouldn't be any flow of fuel to the carburetors.

[ekpent]

 For the sake of others who may be looking and if they are proved to be truly junk items please mention where you bought them so others can assess the risk in purchasing.
  If your carbs are clean etc. the overflow should come out the brass tubes/rubber hoses at the bottom of the carbs and piddle on the floor on your 750. If they are plugged gas can possibly seep into the engine and air box.

[whitjonw]

Carbs are clean, fuel pisses out of the overflow tubes as it should.


Let's figure out if others have had this issue before and what they did to rectify it. Petcocks are from Vintage CB750. I would hesitate to call them junk and they appear well made otherwise, but the valve isn't sealing like it should when in the off position.

This is what I am working with:

[ekpent]

 The bolt and washers 'look' correct. There is also a rubber seal with 4 holes in it under or behind the on/off lever,at least on stockers that could be the issues. Are the screw tight on that outside plate,hopefully not riveted.  Were those red washer gaskets super tight to the bolts and almost needed to be screwed on ? I bought some Honda ones a few years back that were super tight on the bolt so that may be a good thing.

[Stev-o]

I no longer buy re-pop petcocks, I've had a couple fail as well.

Turns out they cost more money as they need to be replaced...