I have a US 41 that is in a big Fly Baby. The engine runs fine when on the ground and runs good in air for about 4 minutes and then it dies. Once I get it back down it is extreemely difficult to start again. Could it be that it is getting too hot? It doesn't really seem to be too hot when I check it. This is my first gas engine so I don't know much about them but if anybody has any ideas as to what I may be doing wrong I would be gratefull.