Brut crankshaft question

[brutus]

Hi there
New here so if you see a way to improve my post, let me know.
I have the crank from my Brut 440 on the bench and there are corks in the round pieces which hold the rod pins.It appears I am missing some of them, but I fail to understand what they do. Do They have to be in there? What is the purpose? Seemed strange to have cork in my engine!! Hope you can help. Thanks all!

[obj1]

The corks were put in there to de-crease crankcase volume. Less area in the crankcase for the air/fuel mixture to hide so more of it ends up in the combustion chamber. cork is used because it wont hurt the engine if it comes loose. So if your ever racing your buddy and you see cork flying out his exhaust, he's cheating on you!

[brutus]

Thanks obj1, makes sense, just never came acrossed it before. Not really needed then?