Topic: Petcock CB 750 fix or change ?

[aminemed]

Hi all

Yes another leaking petcok topic! I've read them all but can't find the answer to my question. My petcock even if in OFF position is leaking. I'm trying to fix it. I want to check if I'm on the right track. Based on my observations and the attached picture, when petcock is in off position:

1) I remove petcock screws (number and fuel is leaking from number 4.

2) It's also leaking from the brass tubes but those are attached directly to the fuel lines so there no fuel leaking on the bike itself.

3) When I open cap fuel (number 2), it is full of fuel and some gas is leaking from above. Checked, screws are tightened really really well with the specific orange washer.

So what can be the best cause ?

Another issue I do have is when I'm on reserve, no fuel is available.

[evinrude7]

my guess is you have part #4 set into the petcock incorrectly.  examine the part for how it should be oriented.  if oriented correctly you may want to replace that particular part.  tiny handle parallel to the ground should be off, pointing up (handle down) fuel on, pointing down (handle up) should be reserve.  i think. 

[aminemed]

if #4 is pointed correctly, petcock does not leak at all ?

[evinrude7]

couldn't tell you if that's the problem from here.  you said it was leaking from #4.  i assume you mean part #4 in the exploded picture.  could be it. 

[evanphi]

Take the whole petcock off and clean all the passages. Clean the filter screen. Order new rubber parts.

[Edwin_SOHC]

Go as Evan suggests, take it off, disassemble, clean, new rings.
On your topic no fuel when on reserve: probably the tube inside the tank is shortened or removed. I ran into same issue.
All things considered, 50 bucks are going to get you a brand new one ...

[Johnie]

Agreed...nothing more aggravating than a leaky petcock. I just put new on all the bikes and be done with it.