newbie with a carb leak

hey guys new to this site and reading around you guys seem like great help, and I just got a 79 KZ1000

ST I've never worked with motorcycle engines before and my carburetor on the left side keeps

leaking out of the overflow and I was just wondering if I can get some help on what is wrong and what

needs to be done to fix it. thanks in advance.

Sounds like a stuck float.

Stuck float is definitely a possibility.
Does it leak when motor is shut off also?
If it leaks when motor is turned off and it has vacuam petcock it could also be part of problem,can you post a picture of the petcock on your tank?

Fuel coming out of the overflow hose (the little hose on the bottom of the carb) is the common symptom of the 3 possible problems described below. Remember – NO SMOKING or other activities that could ignite the fuel while working on carbs!

The float valve is not sealing. This may be (and probably is) just a matter of some minor dirt in the float valve and is very simple to remedy and can be done with the carbs still on the bike. Turn off fuel; drain carb by loosening big brass screw near bottom; and remove the 4 little screws on the bottom of the carb bowl. This will enable you to remove the carb bowl. You will then see the float. If you carefully remove the float you will see a stubby little needle that mates with a brass orifice; together, these two pieces are the float valve. Assuming there is no obvious damage to the needle or seat, use a Q-tip and some carb cleaner to clean the seat of the orifice and the needle. Be careful not to bend the tang that is attached to the float. This tang is the piece that the bottom of the float valve needle rests upon, and it determines the fuel level in the bowl, so bending it will change the fuel level. With the float valve cleaned it should no longer leak. To prevent a reoccurrence a quality inline fuel filter should be installed between the fuel tank and carbs. If there was damage the needle and seat should be replaced as a set; they are available.

The brass overflow tube inside the carb bowl is damaged. When you remove the carb bowl you will see a brass tube attached inside and rising toward the top of the bowl. This is the overflow tube and it leads directly to the overflow nipple on the bottom of the carb. Normally, the fuel level within the bowl rises somewhat close to the top of this tube. If the tube becomes cracked or separates from the bottom of the carb bowl fuel will flow through it and out through the overflow hose. Checking the condition of the tube is very easy after you have removed the carb bowl from the carb. Simply hold the bowl level and fill it up near the top of the tube with water of alcohol and see if it leaks. If it does the best remedy is to replace it although some folks have found creative ways to repair them.

The fuel level is set too high. This condition occurs when someone has bent the float tang as mentioned above. This condition can be checked using what is referred to as the “clear tube test.” The test involves attaching one end of a clear piece of flexible tubing to the carb drain hole and holding the other end of the tube above the bowl/carb joint. When the fuel is turned on it should rise in the tube to a level 2.5 – 4.5 mm below the bowl/carb joint. If the fuel rises higher than that level it may run into the cylinders or over the upper end of the brass overflow inside the carb bowl (mentioned above) in which case it will run out the overflow hose. This condition is corrected by removing the float and gently bending the tang to raise the float valve needle position. Doing this may take several tries before achieving the desired fuel level.

Correcting each of these three conditions involves removing the carb bowl. This task can be made easier if a short screwdriver bit is used, and depending on which carb you are fixing a mirror may help you locate the screws on the bottom of the carb bowl. Also, it is not a bad idea to have a new carb bowl gasket available in case the old gasket is damaged while removing the carb bowl. Ed

my fuel level sensor is leaking all over my carbs, I got a new gasket and a full tank of gas. have you looked at the tank?

I took the bowl cover off and my float has good spring and doesnt stick I'm going to pick up some

carb cleaner and clean the jets and float valve and see if thats the issue. thanks for the response

guys and ill try to get some pictures up.

set the float bowl in a jar so the top gasket surface is level and facing up and fill the float bowl with liquid of your choice. wait a few hours and see if any leaks.

How much is it leaking? Does your bike have a vacuum petcock?
If it's an occasional small leak, then it may be the fuel-valve/petcock.

when there's gas in the tank it acts like it fills up the carbs and then dumps it out the over flow

but that's when the petcocks is on, if i shut the petcock off it doesn't leak so it isn't a petcock

issue

Where is OFF on your petcock? I have a 79 KZ1000 ST, as well.

It's fairly typical for a bike to leak if there is fuel flow from the tank... that's why it is often recommended that the valve be placed in the off position when the bike is parked. However, your problem may very well be w the float needle valves &/or seats. It's just something to consider. My bike sporadically drizzles a little fuel when inadvertently left in PRI.

the last thing you want is gas all over you.