TOPIC:

New to this community and my knowledge is limited so please bear with me. I already searched for my issue.

I recently bought a 78 kz650 4 cyclinder.

The previous owner kept it stock and went through the bike and replace the typical things you would replace on an older bike.

He also put in a new carberurator unit. I know so because I have the old one.

Today I got some gas to see if it would start.

I was pouring the gas and realized it was leaking profusely.

I then realized the petcock was in the prime position so I moved it to the reserve position.
This slowed the leak by a lot.

With that out of the way I observed the bike and noticed gas goblets collecting around screws on the bottom of the carbs. None of the gas was leaking via the overflow hoses, which dumbfound me.

I'm assuming the one of the floats may be stuck.

Hoping I don't need to take the carbs off. If that's realistic please let me know.

Also if anyone can explain how they run the vent and overflows hoses also would be great.

Pics for reference h

The bottom of each carb bowl has a nipple for overflow. Hoses should be attached to them and those hoses should terminate behind the engine pointing toward the ground. Carbs #2 & #4 have vent nipples on top that should have hoses terminating into the atmosphere near the air box. Carb #2 will have a nipple on top toward the engine end of the carb that connects to the stock petcock. It provides vacuum to operate the petcock when the engine is running. See image below.

Regarding carb overflow -

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 re-occurrence 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 or alcohol and see if it leaks. A slight crack in the brass overflow tube can be difficult to find. You can connect a rubber tube to the overflow nipple, fill the bowl with water, put finger over the open end of the brass overflow tube and blow in the rubber end and look for bubbles. 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