The stock squish varies based on Deck Height. The stock head gasket typically measures .045". Now add your Deck height measurement to it, or subtract it if the piston sits Above the cylinder and that will tell you the Squish. The only way to know is to measure everything.

We use a formula to determine how much to mill off. It requires measuring the size of the combustion chamber (CC'n the heads).

 

I guess my question was more that there is no uniformity to what the squish measurement was on a stock motor off the line. It can't be said that Harley manufacturered all Evo's for a squish measurement of .___ stock.


Are there any benefits to a set of aftermarket performance heads over having stock ones worked?

I'm getting that I would benefit from having my cylinders milled to a.)Prevent base cylinder gasket leakage, and b.)Ensure a proper squish measurement. The next step would be to have the heads milled. These things would be, from what I understand, basic machining changes that would cause the engine to produce more power more efficiently without adding workload stress. After this, it appears, changes become a little more dicey in regards to reliability. I'm formulating off-season plans for what we've been discussing.

 

You could have just thumped me in the melon to make me look at the bigboyz webpage to answer the second part of my last question. There is alot of good info on that page that makes alot of sense. Thanks.