
Originally Posted by
cheese
There was a crazy mod people were doing a few years back where you drilled two holes in the back of teh piston. No idea what that was about...
Jeepers Cheese??? You should know this??
Your own bike has them from factory??
Here 2004 Cr250 Piston

They are called boost port windows or Transfer port windows in the piston.

They let extra fuel into the crankcase as the piston passes the inlet port. So when the piston comes down it has more to push up the transfer ports?? I suppose it lightens the piston but that is not the main purpose. Its about stuffing more fuel into the chamber. We did this to our kart pistons, or made them bigger.
Early bikes or non performance bikes didn't have them so they where drilled or machined in.
On a Motorcycle you're penetrating distance, right along with the machine!! In a car you're just a spectator, the windshields like a TV!!
'Life's Journey is not to arrive at the grave safely in a well preserved body, but rather to skid in sideways, totally worn out! Shouting, ' Holy sh!t... What a Ride!! '
Bookmarks