I have an old yamaha 250 moto 4. I rebuilt the carburetor. Put a new airfilter on it. It starts just fine. It runs great in the first 3 gears, when I put it 4th it bogs out alot. Sometimes it dies. Ive adjust the float. Wondering if you had any ideas what may be causing this. I seem to think the carb is is running out of gas? Dont know and Im starting to get fustrated.