Problem Filling Fuel Tank - Troubleshooting:
So you only manage to get 10 – 12 L in each time you refuel?
What to do? First read the previous wiki article as this explains the design of the fuel tank, and the components that are mentioned here.
Now blow through the overflow tube to test if all lines are clear. This is the black rubber hose hanging down on the left hand side of the bike just in front of the gear lever – so confirm that air comes out of the overflow hole -#1 and the rubber grommet -#2 (both under the fuel cap).
And then with those 2 blocked with your fingers, you should hear air bubbling back up through the tank, as the air will flow back through to the fluid recovery reservoir -#4, then the reservoir breather valve -#5 and from there in to the tank. 4 & 5 are found underneath the pillion seat.
So if you do hear the air bubbling back into the tank: this will point to the reservoir breather valve -#5 - being the faulty component. So this needs inspecting....carefully: Undo the 6 screws, remove the metal retaining plate, then gently prise up the unit. Be cautious as if the inner valve piece has freed itself from the main body, it may drop back into the tank So remove this slowly and just in case have a pair of tweezers handy and nimble fingers!
If the unit comes out in one piece, the first thing to do is turn it upside down and check if the 3 retaining tabs are firmly clicked into place. If not, this may prevent the valve from freely moving up and down inside the unit. You should be able shake the unit and hear the components moving inside.
Mine only had a single tab clicked into place, so from there I disassembled the unit and put the inner valve and spring back in alignment and then reassembled - it takes a firm push to click all 3 tabs back in. I reassembled it, and finally, after 12 months I am able to get in 20L again!
So if the airways are blocked you need to isolate where:
Start by disconnecting the hose from the metal connector that goes into the tank from #4.
Blow again and confirm that air escapes from the metal connector - one owner found this was blocked with a silicon plug (assumed to be left over from the tank painting process).
So if air escapes here, blow into the reservoir tube you have just disconnected to make sure the blockage is not there – unlikely!
From reading other entries, it does appear that 90% of the issues point to a faulty reservoir breather valve - and the majority of those because the 3 tabs were not correctly in place.