had similar problem to pocket rocket but this was definately mechanical we belched blue smoke then stopped bike. it still smoked when we tried to restart and wouldn't fire.has anyone managed to get nearside piston out through bottom of engine. we got the other 3 out this way
I have an nc29 upper crank case on the shelf at the mo that someone has tried to remove the pistons from below - all the pistons are now stuck and need the rings butchering off to get them out.