I bought a 2003 400ex acouple days ago I have been able to ride it ones the the last time I rode it I was riding down the rode maybe giving it half throttle
when I heard a pop and noticeed that oil was draining out of the engine so I pulled over and shut the 4 wheeler off. I called my buddie and had him pull me home. When I got home I tryed to start it and it didn't seem to have any compretion. So I asummed the head gaskit blew. So I took the motor apart replaced the gaskit and saw the it did blow actually blow. So I put it back together but it didn't start. I replaced the spark plug thinking that it may have fouled the plug it sill didn't start so i sprayed starting fluid into the air box still didn't start. Please give me your opinion.