Hi,
I have a Hobao Hyper 10 with a Force 15 motor.
It is an old car and I have been having trouble recently.
The engine seems to 'seize' every now and again.
I can run the engine after I rotate the piston manually for a while by turning the crankshaft (I think that's what it is called) using a spanner where the pull start fits.
After the engine freezes there is lots of resistance when the piston is at the bottom of the cylinder.
I need the leverage of the spanner to break free of the resistance and continue moving the piston.
after a few minutes of turning I can turn the motor using the pull start and eventually the resistance is low enough to allow me to start the motor.

Any suggestions on what could be causing this or how I can fix it would be greatly appreciated.
Sorry for such a long post.
Just ask if you require more details.

Thanks HEAPS!!!
Daniel

tear the motor down, and look inside. you will probably need to replace a few things.

Yeah I have done that and it appears that the piston is catching on the top of the ports.
Also the top of the piston has a rugged feel with almost like stone chips in the top.

Does this mean I have to replace the piston?