Ok so I just finished timing my valves and now my bike has low compression and won't start. It has a brand new wiseco piston rebuild with less than an hour on it. I took apart my motor because it was backfiring, running bad, and somewhat easy to kick over. I shimed the valves, checked my clearances, and timed the valves as well. Now it's back together and it won't start and feels very light to kick over. What could be the issue?