This is a quick little modification to a head for my Peugeot 103. The volume of the decompresser chamber is fairly large on these heads. So it seems like in the end you end up reducing the compression ratio a pretty good amount with the stock head, at least thats what it seems like to me. So I tried a little experiment on this malossi head. I tapped and inserted a set screw in the exit port from the combustion chamber to the decompresser valve. I also filled exterior port with a plug as well just to make sure it's completely sealed up all the way.