ok guy ive just blown the exhaust gasket on the 66cc, last night when i was looking on here i seen a pic of the exhaust port and when the piston was top dead center you could look through the port and see the bottom of the piston , well just took the exhaust of to check mine and when the piston is top dead center the whole port is covered by the piston , on the bottom stoke you can see the top of the piston is this right ? the bike runs fine but could go alot better