Small Engines (Lawn Mowers, etc.): atv, air fuel mixture, tank lines

Question
Please help me ,   I  have a Bombabier ATV 400 Outlander single cyl. carb fired engine.  It starts fine , but when it gets hot it wont restart, unless I remove the air filter?  I have dissassembled and cleaned the carb,tank,lines,cap,filters and new plug. Why when I remove the CLEAN air filter it starts?????  please help.

Answer
I don't have a lot of experience with ATV's.  So you may want to check with someone else.  Are you sure that nothing else is happening when you remove the filter.  Sometimes one action will cause another action and that would be your issue.  But if the engine will not run with the air filter in place the engine is running to lean.  By removing it your allowing more air into the air/fuel mixture.  I'm confident that you have check things like spark arrestor being plugged on the muffler.  The only other thing I could think of would be warpage of an insulator block where the carburetor mount.  Hope this information has been of some help good luck on your project.