i had the same problem with my beta, the trick is put the bike on a stand so the front wheel is barely touching the ground, pull both caps off, pull the drain plugs, grab the front wheel and compress the forks a few times to make sure they are drained, put the plugs back in, find a block of wood or some thing to put under the front wheel so the forks are up as high as they go, fill the forks with the new oil and hold the front tire up remove the block and slowly let the wheel down, (work it up and down while you let it down, but 310cc sounds right, that all may not fit when the forks are compressed, once you work them down to fully extended ad the rest and cap them off and there you go!!!! it's the long hard way but it worked for me, i had the exact problem, what it is, air gets trapped in the oil and creates a false bottom, just like any hydraulics, they need bled, hope this helps out.............................JOHN