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RSRBOB, Technician
Category: Motorcycle
Satisfied Customers: 1078
Experience:  Former Factory Service Rep, Dlr Line Tech, Service Manager, General Manager, Store Owner
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I have a 1990 Yamaha FZR 1000 Motorcycle with the stock CV

Customer Question

I have a 1990 Yamaha FZR 1000 Motorcycle with the stock CV carbs> I am trying to set the float level. I set the floats using the "tilt the carbs until the needle valves are closed" method and measured from the carb body to the top of the float. I set them all to an internet recommended 14mm. Now I am checking the float levels with the Factory Yamaha service tool YM-01312 (graduated plastic tube) and following the manual instructions the carb level should be 10.6 to 11.6mm above the line on the cabs float bowl cover. My float level stays about right at the float level line no matter where I move the graduated cylinder. It means my float level is too low?
Submitted: 2 years ago.
Category: Motorcycle
Expert:  RSRBOB replied 2 years ago.

HI and thank you for your question.

Using the glass tube allows you to see the fuel level inside the float bowl. Therefore, the fuel level should not change just because you raise or lower the tube. You are not altering the fuel level inside the float bowls by moving the tube so it isn't going to change. You can move the tube up and down so you can get the graduations set to make it easier for you to read the MM. The fuel level spec from Yamaha is actually 10.5~11.5 mm above the line cast into the outside of the float bowl. The 0.1mm is so insignificant it isn't worth worrying about. If your fuel level is between 10.5~11.5mm above that line then the fuel level is correct. Be sure you synchronize your carbs too. That is a major factor in how the engine responds to throttle and bottom end acceleration.