Leaking Carbs

[rsercb]

Is there a cure for leaking carbs ?  I am working on a 1974 Honda 750K
The float needles have been replaced and the carbs still tend to leak into the overflow tubes.
Sometimes the floats get stuck down and the fuel flows out the intake of the carb and into the air box.
Like I said the float needles/shut off valves have been replaced. Are there upgrade floats and shut off valves available ?

[Re-run]

If this happens a lot, you might have cracks in your floats. I would take them out and float them in some gas and see if they sink at all. While doing that, you replaced the needles but did you give the seats a good cleaning? If not, no needle in the world will seal right.

[woodsrider250-2]

Good advise.  

I always lightly burnish the seat with some lapping compound on a q-tip.

[rsercb]

Hey thats a good idea. thanks.  I was wondering if they make a rubber tipped valve for the 750's. I've seen rubber tipped valves on some of the dirtbikes I have worked on.

[waddellpc-3]

Hi,
I've just removed the carb rack because I was having same problem - gas would just run right through the carb into the air box - I'm not sure how to diagnose which carb(s) is the problem. The bike was sitting for 7 years.
-  so wondering if anyone has some insight or can direct me to a 'how to' link I can look at for installing carb rebuild kit to solve this problem.  
2. in your experience, what are chances of problem being solved by just cleaning needles and seat and checking float levels w/o replacement kits....I've done this once before with an in-line 4 but only taking off float bowls and adjusting float levels on 1 carb.
3. where is best place to get a carb rebuild kit?
4.  also, any ideas on how to determine which carb(s) needs rebuild kit? all 4 to be safe? (bit expensive) or just be examining each on the bench will do it ?...
any feedback would be great. thanx.
Rob 78 cb750K

[woodsrider250-2]

Indeed.  In the days of ethanol 'enriched' gas, this is probably a good thing though.

[rsercb]

Not following you.  Are you saying.....yes you can get rubber tipped valves ? And is your concern that  ethynol may "attack" the rubber ?

[Re-run]

I haven't seen any new needles that are NOT rubber tipped. My originals were and the replacements were. But you still need to clean the seats.

[rsercb]

Thanks, I'll clean the seats and pursue getting some rubber tipped needle valves.
Any suggestions on a good source for Carb parts ?

[woodsrider250-2]

http://z1enterprises.com/

Other places have them, but I like supporting the guys that specialize in keeping these old bikes alive.  Their prices are good.

[brcree]

  Hey, my cb 750 6k did the same thing, I cleaned the fuek system and put in a inline fuel filter....seemed to do the trick!

[Chaps]

My Dad's '77 K model was running like a champ- little misfiring unless under at least a little throttle or at 5k or above rpmwise - but has been pretty decent for about 3 years, until I used a pressure washer on it. Now unless the fuel switch is on "off" it will leak out of the #2 intake (not bowl or any exterior fuel vent/passage) and down the airbox and drip all out on the ground. what happend when I pressure washed it?? lol

[TOOLS1]

"what happend when I pressure washed it??"
You broke it. Welcome to the forum. I have no idea why it would drip from the no#2 carb. I would bet it is the fuel line, or petcock. Also it could be one of the O-rings, for the fuel line fittings.
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[hc243102]

Just rebuilt my carbs, same problem. Leaking from #1 and #2 drains. How would the fuel line or petcock affect this? I was using a dirt bikes gas tank to test the carbs.

[TOOLS1]

It wouldn't. Your floats are set too high.
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[seestheday]

hc234102 you don't have the year of your bike in your sig.

Different years have different carbs.  E.g. my 81 does not have adjustable floats so they can't be set too high, but they can definitely stick or not seat right.