I have a little concern about the transfer ports on my DrEvo, see the pictures.


As you can see neither the transfer ports nor the exhaust port is fully opened, it may differ more than half a millimeter.
It doesn´t feel right to not use the full openings but how much power is there to lose?
I can cure it bu putting a number of gaskets under the cylinder but then I will loose compression unless ia take away some on top of the cylinder.
Can I take off some material on top of the piston without a problem?
It seems like the easiest way to deal with this.
How much close to the top ring can I go before it gets too close?