We had the same problem on another bike, it was the fuel pump.
Either the pump is weak or the pre filter or post filter is getting clogged.
We took the tank off and performed this test below....
put a 3/8 hose on the pump outlet make sure it's tight when it goes on or with a hose clamp.
Make sure the hose has enough length to circulate back into the tank where u fill it up at, we had a 3' hose.
We got a car 12 volt battery and connected the positive & negative on the pump and let it start pumping.
We watched the flow rate, at the beginning it didn't pump worth a dam, like a stream the size of the lead in a pencil out a 3/8 hose.
We took the entire pump apart & the pre filter was caca, we replaced it with a car one , we made it work & then cleaned the post filter as it was dirty also.
Put it all back together, hooked everything back up like on our first test.
The fuel came out full flow out the 3/8 line, now the size of a pencil. Yes we're good.....
Then one minute later back to a the same stream as before. Pump is no good..
Now we just ordered a new pump for it, waiting for it to come in.
$330 for a new fuel pump assembly online sux, but it was the cheapest anywhere and the dealership here price matched it.
