problems with pistons

[MacDaddy]

I just got to read about the famed 2100 I have seen some fast 2100s and never one with a hole like that, what was that hole for mike or is that new tech we have to pay for first

 

[dneiger]

If I am correct the hole high in the piston as shown corresponds with a trough cut in the cylinder wall above the intake port, it acts like a boost port by feeding the port through the hole. We used to call them puff ports, they seemed to work up to a point, sometimes we would put 2-3 of them in depending where the ring or rings were pinned.
Dave

 

[ehp]

I have a 090 from Marcel built in the mid 70's with that kind of port and hole in the piston, works ok for over the block but not to good for cold start,

 

[bwalker]

Maybe the hole is there to feed a poofter port.

 

[064 stihl]

Does anyone have any pictures of these? Do they help?