Sounds like you're starving for fuel.. Check your lines when this happens. If the float bowl runs dry due to a restriction causing the fuel not to flow fast enough you will have this problem.
getting ready to mod my frame keeps cracking at the cantilevers near post I ride fast-gona hack off back half of frame and weld in a pivot and air bag I have it has a narrower height so I'm going to do a track bike tipe set post down low