card leaking....need advice bad...please help

first off thank you for any advice....ok my issue is i own a 1978 kz 650..stock carbs vm24..stock..air box...well stock bike....i am the second owner of the bike...my father bought it brand new...it was handed down to me...anyway to the point..number 4 carb is leaking out the over flow...constant drip,drip,drip....i do know some about carb work....i have rebuilt all four...the have..stock jets sizes....i havw new needle valve and seats....i have adjusted floats fuel level ..both dry method and wet method...fuel level was set wet at 3mm....of course i have tried many setting from 2mm all the was to 5mm....i have cleaned the carbs a number of times.....with compressed air...carb cleaner ..even ran torch tip cleaners through em...carbs are spotless.....i have also check for float getting stuck on bowl i have hit with rubber mallet...even went as far as buying new floats...what am i overlooking ? please any info
ps..bike runs fine...just constant drio of gas out overflow

1. Is there any grit/rust in the tank? The smallest of particles will cause over flow. If so clean the tank.
2. Have you put on a fuel filter just to be 100% sure no grit reaches the carbs? If not fit a fuel filter.
3. Does the petcock close properly?
4. Change fuel lines, there might be grit in them that loosens an make its way in to the carbs
5. After doing 1 through to 4 clean carbs again, and clean the plastic tubes that connect to the fuel line.
6. Polish the needle seats with an “ear tops” with a mild abrasive like ceramic stove top cleaner.
7. Check the petcock once more.
8. Test the carbs on the bench with clean gas from a bottle.
9. Refit and try again.
Best of luck

/A

I’ve had this problem as well.

I don’t trust the float valves because they are marginal at best for stopping fuel from flowing when they are in the closed position. So I have learnt that the petcock must be completely off when the engine is not running. I replaced the original petcock on my Z650B1 with a ‘Pingel’ type.

Also, how are you adjusting the floats. The Factory Service Manual states that the tang should bent up or down to adjust the fuel level, however if you bend the tang too much it will push the float valve needle at an angle and the valve will leak. Starting with the tang level you can bend the float arms up or down for the coarse adjustment, then fine adjust using the tang. Ideally when the float valve is closed the tang will be level and not at an angle to valve needle.

Brian

You may have a cracked brass tube in the carb bowl. The brass tubes in them sometimes develop hairline cracks and then leak. If you swap carb bowls between #3 and #4 carbs and if the leak moves to #3 carb it's the bowl. Ed

thank ya so much.....i will try that in a few min

Another test method, with bowl in hand, is to just fill it with household rubbing alcohol (or tap water) -- avoids gasoline smell, especially if done indoors -- and see whether the contents exit from the overflow nipple.

Good Fortune!

thank you so much 650ed and patton....just took bowls in bathroom....and i could see crack in tube before i even put alcohol in it...yet i still tested it and drip it did......now my next thing are they a way to fix it or just get new bowl?

Some of the possible repair options would include:

Solder;

JB Weld -- when properly prepared and applied, has proven reliable for the long term while constantly submerged in gasoline, even when used to repair broken float towers;

Slightly larger section of brass tube (from hobby supply store) that fits snugly over the cracked tube and soldered in place;

Section of snug fitting thin-wall plastic tubing over the cracked tube;

Heat-shrink tubing applied over the cracked tube;

Probably others I don't recall off-hand.

If the overflow tube has broken loose where it attaches to the bowl -- that's a more problematic repair situation.

Good Fortune!

ok well first thing i will try is quick steel...kinda like jb weld...if not i go to another option.....i really do thank you guys....its always good to probe someone elses head for info...lol....i have been coming to this site for years ..just never signed up..and usually find what i need buy just reading other ppls post....but this time i had hit a wall....and figured would sign up....once agvain thank you..

As known, be exceedingly careful throughout the procedure not to disturb the connection between the tube and bowl.

Good Fortune!

That JB Weld stuff is a questionable long term fix. Using plumbing solder is more robuts. Get some solder and flux from the hardware store and use a propane torch for the heat source. Scrub the brass tube with scotchbrite before soldering and go easy on the heat. I used that method to fix a cracked brass tube on my 750E floatbowl and the fix went smoothly.