TOPIC:

Can I test the overflow before I reinstall the carb in my bike? 

Yes, rig up a remote fuel tank, rest the carbs upright in the vice, turn the fuel on, see what happens. 
Did you get a new needle and seat? 
Whilst you have the test rig set up you should test/set the fuel height in the bowls using the wet method. 


 

Warren3200gt wrote:

Yes, rig up a remote fuel tank, rest the carbs upright in the vice, turn the fuel on, see what happens. 
Did you get a new needle and seat? 
Whilst you have the test rig set up you should test/set the fuel height in the bowls using the wet method. 



 

The seat is built into the carb body.  The needle tip is rubber, so the seat rarely wears.

Thanks warren3200gt. 

I bought a new float valve needle. 

seat?

I’m assuming the one thicker hose from the tank is petrol for both carbs and the thinner hose is the breather/air pipe?

if that’s right, do I do anything with the air pipe, e.g. close it?

wet method?

apologies for continued questions. 

Wet method =
With carbs upright, insert some clear tubing into the drain hole and hold it against the carb body. 
Turn the fuel on and the bowl and tube will fill until the floats raise the needle and shut off incoming fuel. Look where the fuel is in the tube. It wants to be between 2- 4 mm below the mating surface of the bowl/carb body. If it's too high that cylinder will run rich. If its too low it will run lean. 
You adjust the fuel height by bending the float tang that the needle rests on. Bend it up to lower the fuel height. Down to increase it. 
Retest, readjust, until its right. Bit of a faff to do but as the carbs are off, nows the time to do it.

Forget about the seat. Nessism explained you carbs do not have removable seats. On many carbs the seat is removable and matched to the needle so should be replaced as a matched pair. 

Thanks both. 

Re: my assumption about the two hoses. Am I right, and should I do anything with the small hose other than leave it be while I test the carbs?

Blipco, I hear you and I understand. As my carb confidence grows, I feel more able to address all the problems. I will refit the carbs assuming I fix the overflow issue, very short term, then address the rust in the tank. I’ll clean the fuel filter in the petcock this time around and de-rust the tank crud when the next opportunity arises. Meantime, bus to town today . 

I have carb cleaner coming today so I’ll do what I can with that in the fuel bowls. 

The larger diameter hose provides fuel to the carburetors. The smaller tube provides vacuum to operate the fuel valve (petcock). The vacuum tube is not needed for your bench tests.

The factory service manual (fsm) will be a great help.

www.kzrider.com/modules/ServiceManuals/kz440.pdf

Many thanks TexasKZ.

I appreciate the link, cheers. I have a paper copy of the same manual, and it is very helpful. I couldn't find a specific statement about which hose is which, so response is really helpful.

STP carb cleaner aerosol arrived. 

I assume it’s ok to spray the insides of my carbs to help remove the build up of rust particles? I intend to use cotton buds to reach the nooks and crannies of the internal shell, NOT the valves. I’ll then rinse with isopropyl, given I have it handy, to remove both the rust and any cotton left lingering from the buds. 
I’ll gently wash the floats using the carb spray and a toothbrush. 

can I happily spray into the valves too?

If there are better suggestions for cleaning, please holler. 

Needle float valve arrived too. I’ll fit and test after cleaning. 

The idea is to remove all rubber parts including the slides with their diaphragms from the carburetors before spraying the carb cleaner as the cleaner can damage those parts. I don’t suppose you have a set of Japanese DIN screwdrivers?
Anyway, cleaning carbs isn’t that bad but the first time can be a little intimidating. There’s scores of vids on YouTube on the topic. Some good, some bad. 
I do mine in a disposable aluminum baking pan (the rectangle ones made of heavy foil) because it catches the little parts that try to escape.

These type of pans.
 

Thanks blipco. 

I wish I’d realised the risk to rubber before starting. Drat! I sprayed the bowl rubber seals.

the tang is driving me nuts. I cannot bend it without compromising the rest of the assembly. See the circles in the attached. The green length bends as I bend the tang. I have a small vice but nothing prevents compromising the level of the plane twixt hinge and the rest of the assembly. The result is the “stop”, circled in red being taken closer to the body of the bowl. 

I have no idea now how to restore the float assembly integrity 

 

The tang circled in red is the float drop stop and should be approx 90 deg to the float plate. It stops them dropping to the bottom of the bowl allowing the needle to drop so far that it won't then slide back in straight as the floats lift due to fuel entering. If this happenens the floats get artificially stuck down and the carb overflows. 
The needle tang is best adjusted with the floats taken off the carb. 
Lightly grip the float hinge barrel from the back with flat nose pliers. You can the just rotate the whole float assembly in the desired direction which will then bend the tang against the pliers nose keeping the tang straight to the float hinge
Taking the floats out is simple as I'm sure youve found, just slide the pin out.