« previous next »
Pages: [1]   Go Down

Author Topic: Leaking new Honda petcock? CB750 K5  (Read 1034 times)

0 Members and 4 Guests are viewing this topic.

Offline Tugboat

  • Puppet
  • Master
  • *****
  • Posts: 1,778
  • '75 CB750K + '67 CL90 + '71 CT90
    • PseudoMoto
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 »
Logged
If it's worth doing, it's worth doing twice.

Offline CaptFatCat

  • Full Member
  • *
  • Posts: 79
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!
Logged
Resurrecting a Herman Munster CB750 from a few old baskets of K2 and K7 parts.

Offline Johnie

  • Really Old Timer ...
  • *******
  • Posts: 8,606
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.
Logged
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Online bryanj

  • Really Old Timer ...
  • *******
  • Posts: 13,979
  • CB500 Number 1000036
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
Logged
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline CaptFatCat

  • Full Member
  • *
  • Posts: 79
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.
Logged
Resurrecting a Herman Munster CB750 from a few old baskets of K2 and K7 parts.

Offline ekpent

  • Really Old Timer ...
  • *******
  • Posts: 13,512
  • To many bikes-but lookin' for more
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 ??
Logged

Offline Johnie

  • Really Old Timer ...
  • *******
  • Posts: 8,606
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
Logged
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline ekpent

  • Really Old Timer ...
  • *******
  • Posts: 13,512
  • To many bikes-but lookin' for more
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
Logged

Offline Jerry Rxman Griffin aka MuthaF'er

  • This MuthaF'er is getting to be a
  • Really Old Timer ...
  • *******
  • Posts: 14,902
  • Bought her new 4/75
Re: Leaking new Honda petcock? CB750 K5
« Reply #8 on: January 22, 2020, 11:43:15 AM »
Try turning the filter/tube 180*
Logged
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline Tugboat

  • Puppet
  • Master
  • *****
  • Posts: 1,778
  • '75 CB750K + '67 CL90 + '71 CT90
    • PseudoMoto
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.
Logged
If it's worth doing, it's worth doing twice.

Offline Stev-o

  • Ain't no
  • Really Old Timer ...
  • *******
  • Posts: 34,281
  • Central Texas
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...
Logged
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Online bryanj

  • Really Old Timer ...
  • *******
  • Posts: 13,979
  • CB500 Number 1000036
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
Logged
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline Spanner 1

  • Old Timer
  • ******
  • Posts: 4,092
  • CB 750 K0 ( always thought it was a K1!) + CB750K8
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.
Logged
If your sure it's a carb problem; it's ignition,
If your sure it's an ignition problem; it's carbs....

Online Don R

  • My Sandcast is a
  • Really Old Timer ...
  • *******
  • Posts: 19,846
  • Saver of unloved motorcycles.
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.
Logged
No matter how many times you paint over a shadow, it's still there.
 CEO at the no kill motorcycle shop.
 You don't need a weatherman to know which way the wind blows.
Pages: [1]   Go Up
« previous next »