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Author Topic: Leaking new Honda petcock? CB750 K5  (Read 1030 times)

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Offline Tugboat

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Leaking new Honda petcock? CB750 K5
« on: January 21, 2020, 03:28:44 PM »
Bought a new Honda petcock from the dealer for my CB750 K5 and after I installed it, it seems to allow gas through the line when in the OFF position. No gas on the outside at all - just doesn't quite stop the flow. Anyone had that issue before?

Edit: Genuine Honda petcock, screw-on type, not the type w/ 2 screws.
« Last Edit: January 22, 2020, 01:09:24 PM by Tugboat »
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Offline CaptFatCat

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Re: Leaking new Honda petcock? CB750 K5
« Reply #1 on: January 21, 2020, 03:45:03 PM »
I have had this happen on a aftermarket petcock. The quick fix for me was to tighten the screws on the valve base and Presto!
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Offline Johnie

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Re: Leaking new Honda petcock? CB750 K5
« Reply #2 on: January 21, 2020, 04:36:57 PM »
If the 2 gaskets on the screws that hold the petcock to the bottom of the tank are old or the screws are loose you will have this condition. I had it happen on my KO and took the fuel bowl off and put a cup under the petcock. It leaked a drip every 5 seconds with the fuel coming from around those screws. Installed new gaskets and no more drips.
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Offline bryanj

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Re: Leaking new Honda petcock? CB750 K5
« Reply #3 on: January 21, 2020, 04:51:28 PM »
Yes and thin generic fibre washers dont work, Honda ones are expensive but a lot thicker
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Offline CaptFatCat

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Re: Leaking new Honda petcock? CB750 K5
« Reply #4 on: January 22, 2020, 04:58:19 AM »
Its not leaking from valve to tank right? Its leaking through the valve in off position right?

Remove the 2 small screws on each side of the on/off lever to expose the valve and you will find your problem inside.
Easy fix.
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Offline ekpent

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Re: Leaking new Honda petcock? CB750 K5
« Reply #5 on: January 22, 2020, 05:10:08 AM »
Quote from: Johnie on January 21, 2020, 04:36:57 PM
If the 2 gaskets on the screws that hold the petcock to the bottom of the tank are old or the screws are loose you will have this condition. I had it happen on my KO and took the fuel bowl off and put a cup under the petcock. It leaked a drip every 5 seconds with the fuel coming from around those screws. Installed new gaskets and no more drips.
If its actually a K5 its not held on by 2 screws with fiber washers etc. but is mounted on a threaded bung hole. Either the poster is putting the handle in the wrong position to reserve or it has a problem internally. Is the a genuine Honda petcock or an aftermarket ??
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Offline Johnie

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Re: Leaking new Honda petcock? CB750 K5
« Reply #6 on: January 22, 2020, 10:35:15 AM »
Thanks Eric...shows how many K5's I have done  ;D
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Offline ekpent

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Re: Leaking new Honda petcock? CB750 K5
« Reply #7 on: January 22, 2020, 11:03:56 AM »
Quote from: Johnie on January 22, 2020, 10:35:15 AM
Thanks Eric...shows how many K5's I have done  ;D
  A K5 would be way too new for your Johnie !!   ;D
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: Leaking new Honda petcock? CB750 K5
« Reply #8 on: January 22, 2020, 11:43:15 AM »
Try turning the filter/tube 180*
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Offline Tugboat

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Re: Leaking new Honda petcock? CB750 K5
« Reply #9 on: January 22, 2020, 01:08:49 PM »
 Genuine Honda petcock, screw-on type. Yes, fuel passes through the valve in the OFF position but there is no fuel leaking externally.
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Offline Stev-o

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Re: Leaking new Honda petcock? CB750 K5
« Reply #10 on: January 22, 2020, 02:23:44 PM »
Quote from: Tugboat on January 22, 2020, 01:08:49 PM
fuel passes through the valve in the OFF position

I had a new [Kawasaki Z1] petcock leak, I called and complained and they sent a replacement. 
Been good ever since...
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Offline bryanj

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Re: Leaking new Honda petcock? CB750 K5
« Reply #11 on: January 22, 2020, 03:40:13 PM »
We never had K5 in UK went straight from K2 to K6 so have no knowledge of the screw on type but if it is new genuine Honda send it back
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Offline Spanner 1

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Re: Leaking new Honda petcock? CB750 K5
« Reply #12 on: January 22, 2020, 09:27:15 PM »
My K1 750 petcock is also passing gas when 'off' . I thought it was the fiber washers ( it's a 2-screw mount ). New Honda washers and screws and it still passes gas when off. I guess next is a new 3-hole washer in the petcock, 'prolly destroyed by corn gas ! It's about 2 years old.
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Offline Don R

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Re: Leaking new Honda petcock? CB750 K5
« Reply #13 on: January 22, 2020, 09:47:33 PM »
You might try removing the cover plate and flipping the washer over, sometimes this works.
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