81 KZ750 Carbs

I have a 1981 KZ750 four cylinder that is having carb issues. The Bike has Keihin type carbs. My question is about the float valve seats. I was wondering if this piece could be removed or is it pressed in. Out of the four carbs only one is acting up. When the gas is flowing the carb starts dripping out the overflow. I have cleaned the carbs out, not a professional quality job I am sure but they look much better, and I replaced the float valve in the one that was dripping, along with all new gaskets and screws for all the bowls. It still drips. So I was wondering if the seat could come out and if so what was the best way to remove it. These carbs are the only thing holding up bringing this bike back to life after sitting for 5 years in the previous owner’s garage. Any help would be great. Thank you.

1. Pull out the dripping carb
2. Test float bowl for cracks (fill with gas/rubbing alcohol to see if it drips out overflow)
3. Check float level (after ensuring floats are not upside down

Post results for correct course of action

Thanks for the response

Float bowls tested fine (I should of thought of that one)

I am not sure if the float is level but they all seem to be about the same.

You are the second person to ask if the floats were in upside down and all I know is that I put them in the way they came out so I took a picture of them with one on one way and the other on upside down maybe you can tell me which way it correct. The bowls fit on either way so I really don't know and the pictures in the book do not make it clear. The one on the right is the way they were and the way I thought was correct while the one on the left is fliped over.



Thanks for everything

I haven't done anything with my 750 carbs yet (only had that bike about a week now), but on my 250, there was a small lip on one side of the float bar near the pin that holds them in place. If you look at it, it should push up and act as a stopper when the float level drops if the float is installed correctly (I know that's a terrible description, sorry). I might be backwards, but I think you're correct about which one is installed correctly.

~Clutch

Ok so everything has check out so far then and we seem to agree which way the floats go so what is the next course of action?

I know your floats don't look exactly like this, but the thing I described in the previous post is pointed out with a red arrow:

This should be pointed up at you (carb upside down) when float is installed correctly

do you have a manual because if you do please follow the directions to the letter one of your floats is in wrong and yes the float valves are removable they either screw in or are held in by an o-ring down in the body of the carb from you pictures those carbs are full of gunk and varnish so get your self some spray carb cleaner and take all the jets floats float valves and slides out and go crazy with the cleaner from those pictures i'd say at least 2-3 cans of it.let me know if you have any problems

Yea mine have a tab like that on them. So the tab should be able to stop the float when it goes down right?

burkmanofgod wrote:

Ok so everything has check out so far then and we seem to agree which way the floats go so what is the next course of action?

Check float level. You can use a clear tube from the drain valve to see how high the level will be. I actually had the same issue with my 250 a while back. When I opened up and looked at the carb, I looked very closely at the float assembly. When the floats were up all the way, the stopper pin was not pushed firmly blocking fuel flow from the gas tank. I kind of eyeball adjusted and it fixed the problem.

Another thing to check would be where the stopper plug goes into the fuel hole (sorry for bad terms)....you can check for dirt/debris that will keep it from closing completely. Also inspect the stopper for rips/tears/wear. You may just need a new stopper (is it called a float needle?) to fix the issue.

~Clutch

When you say that you "eyeball adjusted" are you talking about just bending the flap that pushes on the float valve?

that is good to start with make sure you put the carbs on abit of an angle so that the weight of the floats arent pushing down on the needles and the bend the tang only enough to get them level if you have to bend any alot it is a good sign that the needles have weak springs and will need to be replaceed.

I agree with timebomb. I got you started, but he is definitely more experienced than I am, so he's the one to trust. Definitely check your manual for setting the proper float levels. Book should also have some troubleshooting ideas in the back to get you started when something comes up.