I just took apart my motor the other day to put a new head gasket in. When i put it all back together it would not start. I was positive i had all the timing right. So I took the motor back out and took the hole thing back apart again and still could not find out what was wrong. I then started thinkin that maybe it did not have enough compression to start. So I checked the valves and noticed the exhaust valve was never going completely closed because it was adjusted so tight. I then adjusted it and put it all back together and it started on the first pull. It ran before I took it apart. Do you think that this valve was like this before I took it apart but maybe just not as tight.

 

When you put it back together you forgot to adjust it properly