Hello, newbie here.  I recently got a 2003 ltz 400 through a series of trades that doesnt run.  The previous owner put new rings and a piston in it lost interest and left it.  I have check the compression, valve clearances, spark and gas and things seem to be in order with all of them.  When i orginally started working on it the timing was off, i have fixed that, it normally would turn over and do nothing after fixing the timing, it pops now through the exhaust but will not start.  Any suggestions?  

This might help.  Another LTZ400 with similar problem: http://www.thumpertalk.com/forum/showthread.php?p=6408856  

Have you tried rolling it off?