125m front sproket removal??

[trikezilla]

I recently bought a 125m motor (1984) and the sproket is shot on it, but I have no clue how to remove it in order to install the new one?? I mean: I cant figure out hou to remove it as it is recessed in to the engine and has a case on either side. I can post pics later also, but currently have no batteries:lol:

thanks

[42F67N]

you have to remove the sub trans to do it.