I was going down the road on my Honda 450 Foreman. I was changing from fourth gear to fifth gear at a reasonable, moderate speed. There was a loud "pop" like a gunshot. This was followed by a clicking sound that started high and went low as I pulled over. Any idea what this could be? Any suggestions on what to check or think about? The four wheeler will now not crank or run. The starter just spins. The top end has been rebuilt. Very recently as in the past few weeks. Any advice or suggestions about possible causes would be greatly appreciated.