I have bought an 2004 ltz400. very strange I can pull start it with another atv. But it wont start with the starter. no problams cranking over. Problam getting worse. now it wont start at all.

 

Could it be just that the starter was going bad and finally bit the dust. Does it make any noise at all when you push the ignition button? If it makes a slight humming noise, it's probably the starter. Do you have an emergency pull start on your quad?

 

Could be tight intake valves. Very common on this motor. The intakes tighten up, and the compression drops way off.