Author Topic: petrol tap woes  (Read 404 times)

Offline mickwinf

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petrol tap woes
« on: May 28, 2026, 01:29:04 PM »
500 four petrol tap, the type with 2 screws holding it to the tank inside the sediment bowl. the one on the bike was refurbed with a kit from nurse Julie and did not leak externally but always had a small flow even when turned off. from previous posts on here I know the seals around the screws are difficult to seal completely, Julie supplies dowty washers which seemed to be an answer but not sure now. The honda ones are stupid price and are now just a standard looking fibre washer. anyway, my carbs started to overflow when left overnight so I thought the steady flow must overwhelm the float needles so decided on a new tap. Not wanting to risk a pattern part I ordered a genuine Honda item along with new washers at great expense. tried fitting today and leaked really badly from the join from tank to tap. After some investigation i have realised the screws are not pulling the tap tight enough and the screws are not fully down although they feel tight and i tried without tap and they screw in all the way no problem. I am completly baffled so having a brew to think. any wisdom out there?
Love the 500 and 550 have a 500 called Lazarus under restoration

Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
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Re: petrol tap woes
« Reply #1 on: May 28, 2026, 02:25:04 PM »
We always tighten the screws to about 7ftlb with a small ratchet and bit. A normal screwdriver just doesn't get the screws tight enough. Had someone here at the weekend, a forum member, with exactly the same problem, once Graham had tightened the screws up properly for him, no more leaks.
« Last Edit: May 28, 2026, 02:28:14 PM by Nurse Julie »
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Offline mickwinf

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Re: petrol tap woes
« Reply #2 on: May 28, 2026, 03:19:04 PM »
Hi Julie, the screw was sitting about 2 mm off its seat even with max torque. Ended up putting old one back and so far so good.
Love the 500 and 550 have a 500 called Lazarus under restoration

Offline Bryanj

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Re: petrol tap woes
« Reply #3 on: May 28, 2026, 04:55:54 PM »
They look like standard fibre washers but are about twice, if not thrice as thick