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Gas runs out of the carbs - Keihin CV

30769 Views 16 Replies 6 Participants Last post by  mubeen
I had to clean the carburetors ...... (4x 34mm Keihin CV). As I had the carbs off, I wanted to check/adjust the fuel level height. I “mounted” the carbs on a special made metalplate with the same angel as on the bike. The “gastank” was a 1 L lemonadebottle and the difference from gasolinelevel in the bottle and the bottom edge of the carburettorbody was about 45 cm (approx.. 10 cm more than a full gastank on the bike).
My problem is, that even though the float height is about 17 mm (as they should be) the fuel level height exceeds the recommended max at 1 mm above the carburettorbody many times. The height gets so high that the fuel runs out of the carbs (comes out of the Pilot Air Jet and/or Main Air Jet). Tried it a lot of times now and have even installed new fuel inlet valve needles to try to make up for the failure. I´ve also checked the mating surface of the float needle for corrosion, the upper carb vent lines etc. Nothing´s wrong here - I think.
I can´t figure out what the problem is/what I might do wrong???????????
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This is cut/pasted from my post in another forum, although the carbs are 38mm EXUP mikuni's the procedure is the same.

You may find that if you have Ben the tang and it's not altering the fuel height, then the fuel is bypassing the needle, if you have new (correct) needles, then the needle housing must be worn, or the fuel is leaking past the "O" ring on the housing itself.


This is the procedure to set the FLOAT HEIGHT to 14 mm.

This is not setting the procedure to set the FUEL HEIGHT (as mentioned in the manual) although it should be correct when the FLOAT HEIGHT is set to 14mm

You need to make a gauge like this out of cardboard or an old credit card, the part that sits over the floats needs to be 14mm

You need to fit your new seals/needles etc and then refit the bowl like this to ensure the float is held securely, the jet holder can be fited or not, it doesn't matter

You need to invert the carbs and have them sitting at an angle like this

so that the float is resting on the needle but not compressing it, like this

not like this

You can now use your gauge to set the height that the float sits above the gasket face of the carb, the highest float should just touch your gauge like this.

You have to bend the small "tang" that depresses the centre pin of the float needle to achieve this.

Reassemble the carbs and you're done
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The way you're doing it looks fine, although to ensure the float is sitting securely on the needle, I would tilt the carbs over a bit so that the weight of the float is truly on the needle (without compressing the plunger/spring)

Are all the fuel heights too high? (are all the carbs flooding)

You may have a damaged (worn) needle seat or a bad needle.

If only 1 carb is flooding, try to swap the float and needle to another carb to test whether the fault is in the carb or on the float/needle.
If you look at this website, there's an exploded view of the carburettor

Kawasaki NINJA 2002 ZX750-P7 Carburetor Parts(1/2) - Original Kawasaki Parts | Cradley Heath Motorcycles

As you can see on the diagram, the needle, seat and O ring come as a set (part no 16030) if you've just changed the needles, they probably aren't sealing very well in the old needle housing, which would cause your problem.
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