Carburetor Fuel Flow Problem ?

Hi ! I have a 1982 Yamaha XJ650 Maxim that when the fuel petcock (non original off,on & prime type) is turned to the on or prime position the fuel flow to the # 4 carb is nearly non existent. I opened the # 4 carb drain screw and get nearly nothing. Before I put the carbs bowls back on the carbs I checked the fuel feed t pipe for obstructions by putting air into the t fuel tube and all 4 carbs had air flowing freely from the needle valve seat holders. I need any suggestions from the experts on this forum explaining what could cause a fuel flow issue that I am experiencing. The bike does start but the number 3 & 4 carbs arent't getting the necessary fuel flow. ANY HELP WILL BE APPRECIATED ! DON

 

If the fuel line is clear, it must be the float height.

 

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RICKCOMATIC & THOSE WHO HAVE RESPONDED, I thoroughly cleaned the carbs a couple of weeks ago and I think the needle is sticking in the seat so I will probably have to replace them with new. THANKS FOR RESPONDING ! DON

 

youi can use regular spray carb cleaner if the needle is sticking becuase of gas varnish. carb spray will eat away the varnish.

needles don't usually stick in a closed position. they mostly stick in some type of open position.

your float is probably set wrong. not allowing fuel to enter the bowl.

 

SNOWWY66: I have a question about setting float heights and I hope you can help. I believe the float height is wrong the more I think about it once you explained it to me . The question I got about setting the float heights with a tube and opening the bowl drain screw is this ? Why wouldn't the length of tube or the size of u you create and the location on the side of the carburetor you use for height give different readings if there isn't a consistent length of tube and a consistent point on the carb for reference for the top of the tube to be used for reference ? I understand where the 3mm + or minus 1 is located on the bowl and how the gas rises to a maxium height but wouldn't different lengts of tube and non consistent locating on the carb body give inconsistent readings ??? I bet I have managed to confuse you so please guide me in the right way ! THANKS DON !

 

Don, the tube could go to the floor & back up, but the fuel will always line up with the level in the bowl, something to do with gravity.