#4 wont stop leaking gas!!

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#4 wont stop leaking gas!!

Keanen
Hey Guys,
 this is the first time i've posted to a site like this but I'm currently stuck and want to get some opinions here!

I own an 81 cb750 Custom the thing runs tip-top EXCEPT I can't get the #4 carb to stop leaking gas. I ran some seafoam through the motor to help clean out the carbs first for a few weeks and took the carbs off, cleaned out, replaced all the O-rings and Gaskets. the float looked to be working fine. put it back on the bike, and I'm still leaking. it is coming out of the top of the float bowl but only out of one side of it. (If you are looking at it on the bike, it's leaking from the side you can;t see) did I not put the new gasket on correctly? it didn't look like there were any cracks on the bowl. I'm stumped... If I havent been clear enough or need more info let me know. I'm just really getting annoyed with covering myself in gasoline everytime I try to work in it with no success..
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Re: #4 wont stop leaking gas!!

rich
I've got the same problem on mine 79 750K. It's leaking from the #2 carb though, but it is also coming from the top of the bowl area, not the overflow tube. I haven't had a close look yet but I suspect it's the O-rings in the fuel joint pipes that run between the carbs. Did you replace those when you had your carbs off?

I guess one way to know for sure is to move the tank out of the way so you can get a look at the top of the carbs. put the tank on the seat or a table next to the bike and hook up a long piece of fuel line and turn on the petcock. You should be able to see where it's leaking from then.

This is image from the factory service manual shows the tubes I'm talking about:


I'm not looking forward to taking the carbs off and seperating them. But that looks like the only way to fix it unless it's just the float bowl gasket.
89 VN 750A - Given to son-in-law
79 CB 750K-sold 3 May 21
78 CB 750K
77 CB 750K
77 GL 1000 x 2
77 CB 550F
Holton, KS, US
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Re: #4 wont stop leaking gas!!

Keanen
I changed all the O rings. if it is still the gasket (That I replaced) again, maybe I need to try something different. have you ever tried or heard anything about that "form-a-gasket" stuff that comes in a tube? I dont know if I should try that. or I've head of some metal crunch gaskets...

On Thu, Sep 8, 2011 at 3:58 PM, rich [via Honda CB750'S] <[hidden email]> wrote:
I've got the same problem on mine 79 750K. It's leaking from the #2 carb though, but it is also coming from the top of the bowl area, not the overflow tube. I haven't had a close look yet but I suspect it's the O-rings in the fuel joint pipes that run between the carbs. Did you replace those when you had your carbs off?

I guess one way to know for sure is to move the tank out of the way so you can get a look at the top of the carbs. put the tank on the seat or a table next to the bike and hook up a long piece of fuel line and turn on the petcock. You should be able to see where it's leaking from then.

This is image from the factory service manual shows the tubes I'm talking about:


I'm not looking forward to taking the carbs off and seperating them. But that looks like the only way to fix it unless it's just the float bowl gasket.
79 CB 750K
Holton, KS, US



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Re: #4 wont stop leaking gas!!

rich
Probably not good to put a lot "goop" in the area of the fuel system. The stuff will break down (due to exposure to the fuel) and gum up the fine passages in the carbs and defeat all the work you did cleaning them.

89 VN 750A - Given to son-in-law
79 CB 750K-sold 3 May 21
78 CB 750K
77 CB 750K
77 GL 1000 x 2
77 CB 550F
Holton, KS, US