Join Date: Mar 2018
Location: West coast of Sweden
I had the same problem on my 400....It turned out to be some debris in the needle valve in the float house. By some strange reason Yamaha has not fitted an fuel filter on these machines, witch means even the smallest particles can make the needle valve not to seal. U must take of the carburetor and carefully dismantle the float valve, and I am quite sure U fill fix the problem. I did struggle with this problem for a while as it was coming and going, and I thought for a while that I had to change the needle vale due to wear, but it was just a small debris in it .
In addition U can fit an simple fuel filter on the hose from the fuel shut-of valve to the carb, just to prevent It will not happen again.
Last edited by Tirill; 10-30-2019 at 02:36 AM.