motor siezure?

[pechroc1]

i rebuilt the top end of my 66cc 2stroke. every time i put it together it seizes at the bottom of the stroke. it will only do this when the cylinder and head is on. when i break it down and knock out the wrist pin it unsiezes and when i put it together again and give it a turn it does the same thing . anyone experience this?

 

[bairdco]

is your piston facing the right way? you might have a ring hanging up in a port.

 

[pechroc1]

not a hang up... the piston remains locked until i pop the wrist bearing with the cylinder off...?

 

[pechroc1]

to add: it was a complete topend replacement from the wrist pin and bearing to the cylinder head... all new.