Topic: fuel petcock

[Bais]

I just installed a new petcock on 69 honda cb750.  I tested it on the work bench and when in the stop position fuel still seeps out, albeit more slowly than when in open position.

Is that normal and, if not, any ideas as to what is causing it?

[PeWe]

Leak via the 2 screws that attach the petcock to tank?
Fiber washer ok under screw head?

[Bais]

The leak is from where the hoses will be attached to run fuel to the carburetors.  No leak from the attaching screws at all.  I would have thought the stop valve would prevent any of the fuel from escaping the tank but not sure.

[RAFster122s]

That petcock would be defective in my book...

[Stev-o]

Is that normal and, if not, any ideas as to what is causing it?

Is it an aftermarket part?  If yes, that is normal.  Buy a real Honda part.

[Bais]

Thanks.  It is AM and I thought it may be defective.  I will get a real one and try that.

Thanks all for the input.

[newday777]

Welcome aboard the forum Bais

#1 petcock and #25 fiber washers(2)

https://www.hondaparts-direct.com/oempartfinder?aribrand=HOM&arian=motorcycle#/Honda_Powersports/CB750K1A_MOTORCYCLE%2c_JPN%2c_VIN%23_CB750-1044650/FUEL_TANK_%2b_FUEL_VALVE/39389f3d-6a93-40f5-89af-a09f79bc8f5b/e6d8069b-03cc-4007-af39-5b069cfff871/y

[RAFster122s]

Petcock part # 16950-300-020
(2) gasket fiber washer part # 17993-250-000

Try the discount Honda (Suzuki, etc) dealer prices at South Sound Honda of Olympia, WA…some of if not the best in the nation and shipping charges are reasonable and as economical as they can provide.
https://www.southsoundhonda.com/
They parts look up and ordering website is:
https://shop.hondabike.com

[bryanj]

Without those washers fuel leaks down the bolt thread and bypasses the on/off part getting straight to carbs. Generic fibre washers are too thin, if you can get alloy bodied 6mm hydraulic sealing washers instead of steel bodied they work about 90% of the time otherwise its the expensive Honda ones

[Alan F.]

Your old fiber washers, if intact, will probably still seal for another 50 years.

[beemerbum]

That is the case indeed. The old fiber washers work just fine. I discovered this when I purchased a new OEM fuel valve, a genuine Honda part in Honda packaging. The new piece came without the fiber washers. I used the 49 year old ones and they are fine. No leaks. BTW what is the origin of the name "petcock"? Probably British. Why is the fuel valve named after the genitalia of the male dog?

[bryanj]

Pet is short for petrol and a cock is a form of tap like in "stopcock"
The washers were never included with the tap but always a seperate part

[Romhog]

Pet is short for petrol and a cock is a form of tap like in "stopcock"
The washers were never included with the tap but always a seperate part

I never knew that! Interesting how they got their silly name

[RAFster122s]

A pet cock would be a pet rooster…..another name for a rooster, male chicken, is cock.
Yes, stop cocks are chemistry valves for liquids…. The Dow high vacuum grease we use on our front brake calipers is designed for use in chemistry on stopcocks…

[PeWe]

I'm sure other thing has got it's name after the first kind of cock. It was not silly from the very beginning